publications

2025

1. A&A

   

   The JWST-PRIMAL archival survey: A JWST/NIRSpec reference sample for the physical properties and Lyman-α absorption and emission of ∼600 galaxies at z = 5.0 ‑ 13.4

   K. E. Heintz, G. B. Brammer, D. Watson, P. A. Oesch, L. C. Keating, and 43 more authors

   Astronomy & Astrophysics, Jan 2025

   Abs DOI

   Context. One of the surprising early findings with JWST has been the discovery of a strong “roll-over” or a softening of the absorption edge of Ly\ensuremathα in a large number of galaxies at z \ensuremath≳ 6, in addition to systematic offsets from photometric redshift estimates and fundamental galaxy scaling relations. This has been interpreted as strong cumulative damped Ly\ensuremathα absorption (DLA) wings from high column densities of neutral atomic hydrogen (H I), signifying major gas accretion events in the formation of these galaxies. Aims. To explore this new phenomenon systematically, we assembled the JWST/NIRSpec PRImordial gas Mass AssembLy (PRIMAL) legacy survey of 584 galaxies at z = 5.0 ‑ 13.4, designed to study the physical properties and gas in and around galaxies during the reionization epoch. Methods. We characterized this benchmark sample in full and spectroscopically derived the galaxy redshifts, metallicities, star formation rates, and ultraviolet (UV) slopes. We defined a new diagnostic, the Ly\ensuremathα damping parameter D_Ly\ensuremathα, to measure and quantify the net effect of Ly\ensuremathα emission strength, the H I fraction in the intergalactic medium, or the local H I column density for each source. The JWST-PRIMAL survey is based on the spectroscopic DAWN JWST Archive (DJA-Spec). We describe DJA-Spec in this paper, detailing the reduction methods, the post- processing steps, and basic analysis tools. All the software, reduced spectra, and spectroscopically derived quantities and catalogs are made publicly available in dedicated repositories. Results. We find that the fraction of galaxies showing strong integrated DLAs with N_HI > 10^21 cm^‑2 only increases slightly from \ensuremath≈60% at z \ensuremath≈ 6 up to \ensuremath≈65 ‑ 90% at z > 8. Similarly, the prevalence and prominence of Ly\ensuremathα emission is found to increase with decreasing redshift, in qualitative agreement with previous observational results. Strong Ly\ensuremathα emitters (LAEs) are predominantly found to be associated with low- metallicity and UV faint galaxies. By contrast, strong DLAs are observed in galaxies with a variety of intrinsic physical properties, but predominantly at high redshifts and low metallicities. Conclusions. Our results indicate that strong DLAs likely reflect a particular early assembly phase of reionization-era galaxies, at which point they are largely dominated by pristine H I gas accretion. At z = 8 ‑ 10, this gas gradually cools and forms into stars that ionize their local surroundings, forming large ionized bubbles and producing strong observed Ly\ensuremathα emission at z < 8.

2. A&A

   

   Euclid preparation: LVII. Observational expectations for redshift z < 7 active galactic nuclei in the Euclid Wide and Deep surveys

   Euclid Collaboration, M. Selwood, S. Fotopoulou, M. N. Bremer, L. Bisigello, and 195 more authors

   Astronomy & Astrophysics, Jan 2025

   Abs DOI

   We forecast the expected population of active galactic nuclei (AGN) observable in the Euclid Wide Survey (EWS) and Euclid Deep Survey (EDS). Starting from an X-ray luminosity function (XLF), we generated volume-limited samples of the AGN expected in the Euclid survey footprints. Each AGN was assigned a spectral energy distribution (SED) appropriate for its X-ray luminosity and redshift, with perturbations sampled from empirical distributions. The photometric detectability of each AGN was assessed via mock observations of the assigned SED. We estimate 40 million AGN will be detectable in at least one Euclid band in the EWS and 0.24 million in the EDS, corresponding to surface densities of 2.8 \texttimes 10^3 deg^‑2 and 4.7 \texttimes 10^3 deg^‑2. The relative uncertainty on our expectation for Euclid detectable AGN is 6.7% for the EWS and 12.5% for the EDS, driven by the uncertainty of the XLF. Employing Euclid-only colour selection criteria on our simulated data we select a sample of 4.8 \texttimes 10^6 (331 deg^‑2) AGN in the EWS and 1.7 \texttimes 10^4 (346 deg^‑2) in the EDS, amounting to 10% and 8% of the AGN detectable in the EWS and EDS. Including ancillary Rubin/LSST bands improves the completeness and purity of AGN selection. These data roughly double the total number of selected AGN to comprise 21% and 15% of the Euclid detectable AGN in the EWS and EDS. The total expected sample of colour-selected AGN contains 6.0 \texttimes 10^6 (74%) unobscured AGN and 2.1 \texttimes 10^6 (26%) obscured AGN, covering 0.02 \ensuremath≤ z \ensuremath≲ 5.2 and 43 \ensuremath≤ log_10(L_bol/erg s^‑1) \ensuremath≤ 47. With these simple colour cuts expected surface densities are already comparable to the yield of modern X-ray and mid-infrared surveys of similar area. The EWS sample is most comparable to the WISE C75 AGN selection and the EDS sample is most similar to the yield of the collated Spitzer cryogenic surveys when considering Euclid bands alone, or the XXL-3XLSS survey AGN sample when also considering selection with ancillary optical bands. We project that 15% (7.6%) of the total Euclid detectable population in the EWS (EDS) will exhibit X-ray fluxes that could be detected in the XMM-COSMOS survey, showing that the vast majority of Euclid-detected AGN would not be detectable in modern medium-depth X-ray surveys.

3. A&A

   

   Behind the dust veil: A panchromatic view of an optically dark galaxy at z = 4.82

   Nikolaj B. Sillassen, Shuowen Jin, Georgios E. Magdis, Jacqueline Hodge, Raphael Gobat, and 28 more authors

   Astronomy & Astrophysics, Jan 2025

   Abs DOI

   Optically dark dusty star-forming galaxies (DSFGs) play an essential role in massive galaxy formation at early cosmic time; however, their nature remains elusive. Here, we present a detailed case study of all the baryonic components of a z = 4.821 DSFG, XS55. Selected from the ultra-deep COSMOS-XS 3 GHz map with a red SCUBA-2 450 \ensuremathμm/850 \ensuremathμm colour, XS55 was followed up with ALMA 3 mm line scans and spectroscopically confirmed to be at z = 4.821 via detections of the CO(5-4) and [CI](1-0) lines. JWST/NIRCam imaging reveals that XS55 is a F150W drop-out with a red F277W/F444W colour and a complex morphology: a compact central component embedded in an extended structure with a likely companion. XS55 is tentatively detected in X-rays with both Chandra and XMM-Newton, suggesting an active galactic nucleus nature. By fitting a panchromatic spectral energy distribution spanning from near-infrared to radio wavelengths, we reveal that XS55 is a massive main- sequence galaxy with a stellar mass of M_* = (5 \ensuremath\pm 1)\texttimes10^10 M_\ensuremath⊙ and a star formation rate of SFR = 540 \ensuremath\pm 177 M_\ensuremath⊙ yr^‑1. The dust of XS55 is optically thick in the far-infrared with a surprisingly cold dust temperature of T_dust = 33 \ensuremath\pm 2 K, making XS55 one of the coldest DSFGs at z > 4 known to date. This work unveils the nature of a radio- selected F150W drop-out, suggesting the existence of a population of DSFGs hosting active black holes embedded in optically thick dust.

4. A&A

   

   COSMOS-Web: Stellar mass assembly in relation to dark matter halos across 0.2 < z < 12 of cosmic history

   M. Shuntov, O. Ilbert, S. Toft, R. C. Arango-Toro, H. B. Akins, and 43 more authors

   Astronomy & Astrophysics, Mar 2025

   Abs DOI

   We study the stellar mass assembly of galaxies via the stellar mass function (SMF) and the coevolution with dark matter halos via abundance matching in the largest redshift range to date, 0.2 < z < 12. We used the 0.53 deg^2 imaged by JWST from the COSMOS-Web survey, in combination with ancillary imaging in over 30 photometric bands, to select highly complete samples (down to log M_\ensuremath⋆/M_\ensuremath⊙ = 7.5 ‑ 8.8) in 15 redshift bins. Our results show that the normalization of the SMF monotonically decreases from z = 0.2 to z = 12 with strong mass-dependent evolution. At z > 5, we find increased abundances of massive (log M_\ensuremath⋆/M_\ensuremath⊙ > 10.5) systems compared to predictions from semi-analytical models and hydrodynamical simulations. These findings challenge traditional galaxy formation models by implying integrated star formation efficiencies (SFEs) of ϵ \ensuremath⋆ \ensuremath≡M_\ensuremath⋆ f_b ‑ 1 M_halo^‑1 \ensuremath≳ 0.5. We find a flattening of the SMF at the high-mass end that is better described by a double power law at z > 5.5, after correcting for the Eddington bias. At z \ensuremath≲ 5.5, it transitions to a Schechter law, which coincides with the emergence of the first massive quiescent galaxies in the Universe, indicating that physical mechanisms that suppress galaxy growth start to take place at z \ensuremath∼ 5.5 on a global scale. By integrating the SMF, we trace the cosmic stellar mass density and infer the star formation rate density, which at z > 7.5 agrees remarkably with recent JWST UV luminosity function-derived estimates. This agreement solidifies the emerging picture of rapid galaxy formation leading to increased abundances of bright and massive galaxies in the first \ensuremath∼0.7 Gyr. However, at z \ensuremath≲ 3.5, we find significant tension (\ensuremath∼0.3 dex) with the cosmic star formation (SF) history from instantaneous SF measures, the causes of which remain poorly understood. We infer the stellar-to-halo mass relation (SHMR) and the SFE from abundance matching out to z = 12, finding a non-monotonic evolution. The SFE has the characteristic strong dependence with mass in the range of 0.02 ‑ 0.2, and mildly decreases at the low-mass end out to z \ensuremath∼ 3.5. At z \ensuremath∼ 3.5, there is an upturn and the SFE increases sharply from \ensuremath∼0.1 to approach a high SFE of 0.8 ‑ 1 by z \ensuremath∼ 10 for log(M_h/M_\ensuremath⊙ )\ensuremath≈11.5, albeit with large uncertainties. Finally, we use the SHMR to track the SFE and stellar mass growth throughout the halo history and find that they do not grow at the same rate – from the earliest times up until z \ensuremath∼ 3.5 the halo growth rate outpaces galaxy assembly, but at z > 3.5 halo growth stagnates and accumulated gas reservoirs keep the SF going and galaxies outpace halos.

5. A&A

   

   Euclid preparation: LXI. Cosmic Dawn Survey: ’Pre-launch’ multiwavelength catalogues for Euclid Deep Field North and Euclid Deep Field Fornax

   Euclid Collaboration, L. Zalesky, C. J. R. McPartland, J. R. Weaver, S. Toft, and 195 more authors

   Astronomy & Astrophysics, Mar 2025

   Abs DOI

   The Cosmic Dawn Survey (DAWN survey) provides multiwavelength (UV/optical to mid-IR) data across the combined 59 deg^2 of the Euclid Deep and Auxiliary fields (EDFs and EAFs). In this work, the first public data release from the DAWN survey is presented. The catalogues made available herein consist of a subset of the full DAWN survey that includes two EDFs: EDF North (EDF-N) and EDF Fornax (EDF-F). Each field has been covered by the ongoing Hawaii Twenty Square Degree Survey (H20), which includes imaging from the CFHT MegaCam in the u filter and from the Subaru Hyper Suprime-Cam (HSC) in the griz filters. Each field has been further covered by Spitzer/IRAC 3.6–4.5\textmum imaging spanning 10 deg^2 and reaching \raisebox-0.5ex\textasciitilde25 mag AB (5\ensuremathσ). All present H20 imaging and all publicly available imaging from the aforementioned facilities were combined with the deep Spitzer/IRAC data to create source catalogues spanning a total area of 16.87 deg^2 in EDF-N and 2.85 deg^2 in EDF-F for this first release. These catalogues are referred to as the ’pre-launch’ (PL), as Euclid data is not yet public for these fields and therefore it is not included. Photometry was measured from these multiwavelength data using The Farmer, a novel and well validated model-based photometry code. Photometric redshifts and stellar masses were computed using two independent codes for modelling spectral energy distributions: EAZY and LePhare. Photometric redshifts show good agreement with spectroscopic redshifts (\ensuremathσ_NMAD \raisebox-0.5ex~0.5, \ensuremathη < 8% at i < 25). Number counts, photometric redshifts and stellar masses were further validated in comparison to the COSMOS2020 catalogue. The DAWN survey PL catalogues are designed to be of immediate use in these two EDFs and will be continuously updated and made available as both new ground-based data and spaced-based data from Euclid are acquired and made public. Future data releases will provide catalogues of all EDFs and EAFs and include Euclid data.

6. ApJ

   

   UNCOVER: Candidate Red Active Galactic Nuclei at 3 < z < 7 with JWST and ALMA

   Ivo Labbe, Jenny E. Greene, Rachel Bezanson, Seiji Fujimoto, Lukas J. Furtak, and 27 more authors

   The Astrophysical Journal, Jan 2025

   Abs DOI

   The James Webb Space Telescope (JWST) is revolutionizing our knowledge of z > 5 galaxies and their actively accreting black holes. Using the JWST Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) in the lensing field A2744, we report the identification of a sample of little red dots at 3 < z _phot < 7 that likely contain highly reddened accreting supermassive black holes. Using a NIRCam-only selection to F444W < 27.7 mag, we find 26 sources over the \ensuremath∼45 arcmin^2 field that are blue in F115W ‑ F200W \ensuremath∼ 0 (or \ensuremathβ _UV \ensuremath∼ –2.0 for f _ \ensuremathλ \ensuremath∝ \ensuremathλ ^ \ensuremathβ ), red in F200W ‑ F444W = 1‑4 (\ensuremathβ _opt \ensuremath∼ +2.0), and are dominated by a point-source-like central component. Of the 20 sources with deep Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm coverage, none are detected individually or in a stack. For the majority of the sample, spectral energy distribution fits to the JWST+ALMA observations prefer models with hot dust rather than obscured star formation to reproduce the red NIRCam colors and ALMA 1.2 mm nondetections. While compact dusty star formation cannot be ruled out, the combination of extremely small sizes ( \ensuremath≈ 50 pc after correction for magnification), red rest-frame optical slopes, and hot dust can be explained by reddened broad-line active galactic nuclei (AGNs). Our targets have faint M _1450 \ensuremath≈ ‑14 to ‑18 mag but inferred bolometric luminosities of L _bol = 10^43–10^46 erg s^‑1, reflecting their obscured nature. If the candidates are confirmed as AGNs with upcoming UNCOVER spectroscopy, then we have found an abundant population of reddened luminous AGNs that are at least ten times more numerous than UV-luminous AGNs at the same intrinsic bolometric luminosity.</p> </div> </div> </div> </li>

7. ApJ

   

   UNCOVER: The Rest-ultraviolet to Near-infrared Multiwavelength Structures and Dust Distributions of Submillimeter-detected Galaxies in A2744

   Sedona H. Price, Katherine A. Suess, Christina C. Williams, Rachel Bezanson, Gourav Khullar, and 16 more authors

   The Astrophysical Journal, Feb 2025

   Abs DOI

   With the wavelength coverage, sensitivity, and high spatial resolution of JWST, it is now possible to peer through the dust attenuation to probe the rest-frame near-infrared (NIR) and stellar structures of extremely dusty galaxies at cosmic noon (z \ensuremath∼ 1‑3). In this paper we leverage the combined Atacama Large Millimeter/submillimeter Array (ALMA) and JWST/Hubble Space Telescope coverage in A2744 to study the multiwavelength (0.5‑4.4 \ensuremathμm) structures of 11 submillimeter detected galaxies at z \ensuremath∼ 0.9‑3.5 that are fainter than bright “classical” submillimeter galaxies, seven of which are detected in deep X-ray data. While these objects reveal a diversity of structures and sizes, all are smaller and more concentrated toward longer wavelengths. Of the X-ray-detected objects, only two show evidence for appreciable active galactic nucleus (AGN) flux contributions (at \ensuremath≳2 \ensuremathμm). Excluding the two AGN-dominated objects, the smaller long-wavelength sizes indicate that their rest-frame NIR light profiles, inferred to trace their stellar mass profiles, are more compact than their optical profiles. The submillimeter detections and visible dust lanes suggest that centrally concentrated dust is a key driver of the observed color gradients. Further, we find that more concentrated galaxies tend to have lower size ratios (rest-frame NIR to optical); this suggests that the galaxies with the most compact light distributions also have the most concentrated dust. The 1.2 mm flux densities and size ratios of these nine objects suggest that both total dust quantity and geometry impact these galaxies’ multiwavelength structures. Upcoming higher-resolution 1.2 mm ALMA imaging will facilitate joint spatially resolved analysis and will directly test the dust distributions within this representative submillimeter population.

8. ApJ

   

   UNCOVERing the Faint End of the z ∼ 7 [O III] Luminosity Function with JWST’s F410M Medium Bandpass Filter

   Isak G. B. Wold, Sangeeta Malhotra, James E. Rhoads, John R. Weaver, and Bingjie Wang

   The Astrophysical Journal, Feb 2025

   Abs DOI

   Strong emission from doubly ionized oxygen is a beacon for some of the most intensely star-forming galaxies. JWST enables the search for this beacon in the early Universe with unprecedented sensitivity. Using UNCOVER DR1 JWST/NIRCam and Hubble Space Telescope (HST) imaging data of A2744, we identify strong (rest- frame EW > 500Å) [O III]_5008 emitters at z \ensuremath∼ 7 based on excess F410M flux. We find N = 68 z \ensuremath∼ 7 [O III] candidates, including N = 33 with deep HST coverage required to rule out lower-redshift interlopers (13.68 arcmin^2 with F814W 5\ensuremathσ depth >28 AB). Such strong emission lines can produce very red colors often misinterpreted as evidence for old, massive stellar populations, but are shown to be emission lines where we have spectra. Using this deep HST sample, we derive a new [O III] luminosity function (LF) spanning </inline-formula>, an order of magnitude deeper than previous z \ensuremath∼ 6 studies. This LF is fit by a power law with a faint-end slope of </inline- formula>. Our results are consistent with the z \ensuremath∼ 7 FRESCO [O III] LF across the overlapping 0.5 dex range, . Combining both data sets, we construct an LF spanning 2 dex in luminosity, with a best-fit Schechter function: </inline- formula>, , and </inline-formula>erg s </inline- formula>. There is little evolution between this LF and published [O III] LFs at 3 < z < 8, and no evidence of a turnover at faint luminosities. The sizes of these extreme [O III] emitters are similar to their low redshift counterparts, the Green Peas. The z \ensuremath∼ 7 [O III] LF aligns with the Ly\ensuremathα LF at the bright end, suggesting many of these galaxies are also Ly\ensuremathα emitters.</p> </div> </div> </div> </li>

9. ApJ

   

   COSMOS-Web: The Role of Galaxy Interactions and Disk Instabilities in Producing Starbursts at z < 4

   Andreas L. Faisst, Lilan Yang, M. Brinch, C. M. Casey, N. Chartab, and 49 more authors

   The Astrophysical Journal, Feb 2025

   Abs DOI

   We study of the role of galaxy–galaxy interactions and disk instabilities in producing starburst activity in galaxies out to z = 4. For this, we use a sample of 387 galaxies with robust total star formation rate measurements from Herschel, gas masses from the Atacama Large Millimeter/submillimeter Array, stellar masses and redshifts from multiband photometry, and JWST/NIRCam rest-frame optical imaging. Using mass-controlled samples, we find an increased fraction of interacting galaxies in the starburst regime at all redshifts out to z = 4. This increase correlates with star formation efficiency (SFE) but not with gas fraction. However, the correlation is weak (and only significant out to z = 2), which could be explained by the short duration of SFE increase during interaction. In addition, we find that isolated disk galaxies make up a significant fraction of the starburst population. The fraction of such galaxies with star- forming clumps (“clumpy disks”) is significantly increased compared to the main-sequence disk population. Furthermore, this fraction directly correlates with SFE. This is direct observational evidence for a long-term increase of SFE maintained due to disk instabilities, contributing to the majority of starburst galaxies in our sample and hence to substantial mass growth in these systems. This result could also be of importance for explaining the growth of the most massive galaxies at z > 6.

10. ApJ

    

    UNCOVER: 404 Error—Models Not Found for the Triply Imaged Little Red Dot A2744-QSO1

    Yilun Ma, Jenny E. Greene, David J. Setton, Marta Volonteri, Joel Leja, and 18 more authors

    The Astrophysical Journal, Mar 2025

    Abs DOI

    JWST has revealed an abundance of compact, red objects at z \ensuremath≈ 5–8 dubbed “little red dots” (LRDs), whose SEDs display a faint blue UV continuum followed by a steep rise in the optical. Despite extensive study of their characteristic V-shaped SEDs, the nature of LRDs remains unknown. We present a new analysis of the NIRSpec/PRISM spectrum of A2744-QSO1, a triply imaged LRD at z = 7.04 from the UNCOVER survey. The spectrum shows a strong Balmer break and broad Balmer emission lines, both of which are difficult to explain with models invoking exclusively AGN or stellar contributions. Our fiducial model decomposes the spectrum into a post-starburst galaxy dominating the UV-optical continuum and a reddened AGN being subdominant at all wavelengths and contributing at a level of \ensuremath∼20%. However, this model infers a stellar mass of M_\ensuremath⋆ \ensuremath≈ 4 \texttimes 10^9 M_\ensuremath⊙ within a radius of r_e < 30 pc, driving its central density to the highest among observations to date. This high central density could be explained if A2744-QSO1 is the early-forming core of a modern-day massive elliptical galaxy that later puffed up via the inside-out growth channel. The models also necessitate an unusually steep dust extinction law to preserve the strong break strength, though this steepness may be explained by a deficit of large dust grains. It is also probable that these challenges reflect our ignorance of A2744-QSO1’s true nature. Future variability and reverberation mapping studies could help disentangle the galaxy and AGN contribution to the continuum, and deeper redder observations could also unveil the dust properties in LRDs. *The error code 404 in the title represents that no satisfying model is found for A2744-QSO 1. In computer network communication, the code “404” refers to the error occurring when the server cannot find the requested information.

11. ApJ

    

    The UNCOVER Survey: First Release of Ultradeep JWST/NIRSpec PRISM Spectra for ∼700 Galaxies from z ∼ 0.3–13 in A2744

    Sedona H. Price, Rachel Bezanson, Ivo Labbe, Lukas J. Furtak, Anna de Graaff, and 36 more authors

    The Astrophysical Journal, Mar 2025

    Abs DOI

    We present the design and observations of low-resolution JWST/NIRSpec PRISM spectroscopy from the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) Cycle 1 JWST Treasury program. Targets are selected using JWST/NIRCam photometry from UNCOVER and other programs, and cover a wide range of categories and redshifts to ensure the legacy value of the survey. These categories include the first galaxies at z \ensuremath≳ 10, faint galaxies during the Epoch of Reionization (z \ensuremath∼ 6‑8), high-redshift active galactic nuclei (z \ensuremath≳ 6), Population III star candidates, distant quiescent and dusty galaxies (1 \ensuremath≲ z \ensuremath≲ 6), and filler galaxies sampling redshift–color–magnitude space from z \ensuremath∼ 0.1‑13. Seven NIRSpec microshutter array masks across the extended A2744 cluster were observed, along with NIRCam parallel imaging in nine filters (F090W, F115W, F150W, F200W, F277W, F356W, F410M, F444W, and F480M) over a total area of \ensuremath∼26 arcmin^2, overlapping existing Hubble Space Telescope coverage from programs including the Hubble Frontier Fields and BUFFALO. We successfully observed 553 objects down to m_F444W \ensuremath∼ 30 AB, and by leveraging mask overlaps, we reach total on-target exposure times ranging from 2.4 to 16.7 hr. We demonstrate the success rate and distribution of the confirmed redshifts, and also highlight the rich information revealed by these ultradeep spectra for a subset of our targets. An updated lens model of A2744 is also presented, including 14 additional spectroscopic redshifts and finding a total cluster mass of M_SL = (2.1 \ensuremath\pm 0.3) \texttimes 10^15 M_\ensuremath⊙. We publicly release reduced 1D and 2D spectra for all objects observed in summer 2023 along with a spectroscopic redshift catalog and the updated lens model of the cluster (https://jwst-uncover.github.io/DR4.html).

12. arXiv

    

    Discovery of Ancient Globular Cluster Candidates in The Relic, a Quiescent Galaxy at z=2.5

    Katherine E. Whitaker, Sam E. Cutler, Rupali Chandar, Richard Pan, David J. Setton, and 29 more authors

    arXiv, Jan 2025

    Abs DOI

    Globular clusters (GCs) are some of the oldest bound structures in the Universe, holding clues to the earliest epochs of star formation and galaxy assembly. However, accurate age measurements of ancient clusters are challenging due to the age-metallicity degeneracy. Here, we report the discovery of 42 compact stellar systems within the ’Relic’, a massive, quiescent galaxy at z=2.53. The Relic resides in an over-density behind the Abell 2744 cluster, with a prominent tidal tail extending towards two low-mass companions. Using deep data from the UNCOVER/MegaScience JWST Surveys, we find that clusters formed in age intervals ranging from 8 Myr up to \sim2 Gyr, suggesting a rich formation history starting at z\sim10. While the cluster-based star formation history is broadly consistent with the high past star formation rates derived from the diffuse host galaxy light, one potential discrepancy is a tentative \sim2-3\times higher rate in the cluster population for the past Gyr. Taken together with the spatial distribution and low inferred metallicities of these young-to-intermediate age clusters, we may be seeing direct evidence for the accretion of star clusters in addition to their early in-situ formation. The cluster masses are high, \sim10^6-10^7 M_⊙, which may explain why we are able to detect them around this likely post- merger galaxy. Overall, the Relic clusters are consistent with being precursors of the most massive present-day GCs. This unique laboratory enables the first connection between long- lived, high-redshift clusters and local stellar populations, offering insights into the early stages of GC evolution and the broader processes of galaxy assembly.

13. arXiv

    

    REBELS-IFU: Evidence for metal-rich massive galaxies at z\raisebox-0.5ex\textasciitilde6-8

    Lucie E. Rowland, Mauro Stefanon, Rychard Bouwens, Jacqueline Hodge, Hiddo Algera, and 28 more authors

    arXiv, Jan 2025

    Abs DOI

    Metallicity is a crucial tracer of galaxy evolution, providing insights into gas accretion, star formation, and feedback. At high redshift, these processes reveal how early galaxies assembled and enriched their interstellar medium. In this work, we present rest-frame optical spectroscopy of 12 massive (\log(M_*/\mathrmM_⊙)>9) galaxies at z∼6-8 from the REBELS ALMA large program, observed with JWST NIRSpec/IFU in the prism mode. These observations span emission lines from [OII]\lambda3727,9 to [SII]\lambda6716,31, providing key information on nebular dust attenuation, ionisation states, and chemical abundances. We find lower O32 ratios (average \sim3.7) and [OIII]\lambda5007 equivalent widths (average EW_[OIII]\sim390Å) than are generally found in existing large spectroscopic surveys at z>6, indicating less extreme ionising conditions. Strong-line diagnostics suggest that these systems are some of the most metal-rich galaxies observed at z>6 (average Z_\mathrmgas∼0.4 Z_⊙), including sources with near-solar oxygen abundances, in line with their high stellar masses (average \logM_*/\mathrmM_⊙\sim9.5). Supplementing with literature sources at lower masses, we investigate the mass-metallicity and fundamental metallicity relations (MZR and FMR, respectively) over a 4 dex stellar mass range at 6<z<8. In contrast to recent studies of lower-mass galaxies, we find no evidence for negative offsets to the z=0 FMR for the REBELS galaxies. This work demonstrates the existence of chemically-enriched galaxies just \sim1 Gyr after the Big Bang, and indicates that the MZR is already in place at these early times, in agreement with other recent z>3 studies.

14. arXiv

    Tracing the galaxy-halo connection with galaxy clustering in COSMOS-Web from z = 0.1 to z \raisebox-0.5ex~12

    Louise Paquereau, Clotilde Laigle, Henry Joy McCracken, Marko Shuntov, Olivier Ilbert, and 29 more authors

    arXiv, Jan 2025

    Abs DOI

    We explore the evolving relationship between galaxies and their dark matter halos from z ∼0.1 to z ∼12 using mass-limited angular clustering measurements in the 0.54 deg^2 of the COSMOS-Web survey. This study provides the first measurements of the mass-limited two-point correlation function at z \ge 10 and a consistent analysis spanning 13.4 Gyr of cosmic history, setting new benchmarks for future simulations and models. Using a halo occupation distribution (HOD) framework, we derive characteristic halo masses and the stellar-to-halo mass relationship (SHMR) across redshifts and stellar mass bins. Our results first indicate that HOD models fit data at z \ge 2.5 best when incorporating a non-linear scale-dependent halo bias, boosting clustering at non-linear scales (r = 10-100 kpc). We find that galaxies at z > 10.5 with \log(M_⋆/ M_⊙) \ge 8.85 are hosted by halos with M_\rm h ∼10^10.5 M_⊙, achieving a star formation efficiency (SFE) M_⋆/ (f_b M_\rm h) up to 1 dex higher than at z \le 1. The high galaxy bias at z \ge 8 suggests that these galaxies reside in massive halos with intrinsic high SFE. Our SHMR evolves significantly with redshift, starting high at z \ge 10.5, decreasing until z ∼2 - 3, then increasing again until the present. Current simulations fail to reproduce both massive high-z galaxies and this evolution, while semi- empirical models linking SFE to halo mass, accretion rates, and redshift align with our findings. We propose that z > 8 galaxies experience bursty star formation without significant feedback altering their growth, driving the rapid growth of massive galaxies observed by JWST. Over time, increasing feedback efficiency and exponential halo growth suppress star formation. At z ∼2 - 3 and after, halo growth slows down while star formation continues, supported by gas reservoirs in halos.

15. arXiv

    Investigating photometric and spectroscopic variability in the multiply-imaged Little Red Dot A2744-QSO1

    Lukas J. Furtak, Amy R. Secunda, Jenny E. Greene, Adi Zitrin, Ivo Labbé, and 22 more authors

    arXiv, Feb 2025

    Abs DOI

    JWST observations have uncovered a new population of red, compact objects at high redshifts dubbed ’Little Red Dots’ (LRDs), which typically show broad emission lines and are thought to be dusty Active Galactic Nuclei (AGN). Some of their other features, however, challenge the AGN explanation, such as prominent Balmer breaks and extremely faint or even missing metal high-ionization lines, X-ray, or radio emission, including in deep stacks. Time variability is a unique test of AGN activity. Here, we exploit the z=7.045 multiply-imaged LRD A2744-QSO1, which offers a unique test of variability due to lensing-induced time delays between the three images spanning 22 yr (2.7 yr in the rest- frame), to investigate its photometric and spectroscopic variability. We find the equivalent widths (EWs) of the broad Hαand Hβlines, which are independent of magnification and other systematics, to exhibit significant variations, up to 18\pm3 % for Hαand up to 22\pm8 % in Hβ, on a timescale of 875 d (2.4 yr) in the rest- frame. This suggests that A2744-QSO1 is indeed an AGN. We find no significant photometric variability beyond the limiting systematic uncertainties, so it currently cannot be determined whether the EW variations are due to line-flux or continuum variability. These results are consistent with a typical damped random walk (DRW) variability model for an AGN like A2744-QSO1 (M_\mathrmBH=4\times10^7 \mathrmM_⊙) given the sparse sampling of the light-curve with the available data. Our results therefore support the AGN interpretation of this LRD, and highlight the need for further photometric and spectroscopic monitoring in order to build a detailed and reliable light- curve.

16. arXiv

    

    COSMOS Spectroscopic Redshift Compilation (First Data Release): 165k Redshifts Encompassing Two Decades of Spectroscopy

    Ali Ahmad Khostovan, Jeyhan S. Kartaltepe, Mara Salvato, Olivier Ilbert, Caitlin M. Casey, and 48 more authors

    arXiv, Feb 2025

    Abs DOI

    We present the COSMOS Spectroscopic Redshift Compilation encompassing \raisebox-0.5ex~20 years of spectroscopic redshifts within the 2 deg^2 COSMOS legacy field. This compilation contains 165,312 redshifts of 97,929 unique objects from 108 individual observing programs up to z ∼8 with median stellar mass ∼10^9 to 10^10 M_⊙(redshift dependent). Rest-frame NUVrJ colors and SFR – stellar mass correlations show the compilation primarily contains low- to intermediate-mass star-forming and massive, quiescent galaxies at z < 1.25 and mostly low-mass bursty star-forming galaxies at z > 2. Sources in the compilation cover a diverse range of environments, including protoclusters such as “Hyperion”. The full compilation is 50\% spectroscopically complete by i ∼23.2 and K_s ∼21.3 mag; however, this is redshift dependent. Spatially, the compilation is >50\% complete within the CANDELS area, while the outer regions of COSMOS are >10\% complete limited to i < 24 mag and K_S < 22.5 mag, separately. We demonstrate how the compilation can be used to validate photometric redshifts and investigate calibration metrics. By training self-organizing maps on COSMOS2020/Classic and projecting the compilation onto it, we find key galaxy subpopulations that currently lack spectroscopic coverage including z < 1 intermediate-mass quiescent galaxies and low-/intermediate-mass bursty star-forming galaxies, z ∼2 massive quiescent galaxies, and z > 3 massive star-forming galaxies. This approach highlights how combining self-organizing maps with our compilation can provide guidance for future spectroscopic observations to get a complete spectroscopic view of galaxy populations. Lastly, the compilation will undergo periodic data releases that incorporate new spectroscopic redshift measurements, providing a lasting legacy resource for the community.

17. arXiv

    A confirmed deficit of hot and cold dust emission in the most luminous Little Red Dots

    David J. Setton, Jenny E. Greene, Justin S. Spilker, Christina C. Williams, Ivo Labbe, and 31 more authors

    arXiv, Mar 2025

    Abs DOI

    Luminous broad Hαemission and red rest-optical SEDs are the hallmark of compact Little Red Dots (LRDs), implying highly attenuated dusty starbursts and/or obscured active galactic nuclei. However, the lack of observed FIR emission has proved difficult to reconcile with the implied attenuated luminosity in these models. Here, we utilize deep new ALMA imaging, new and existing JWST/MIRI imaging, and archival Spitzer/Herschel imaging of two of the rest-optically brightest LRDs (z=3.1 and z=4.47) to place the strongest constraints on the IR luminosity in LRDs to date. The detections at \lambda_\mathrmrest=1-4 \mum imply flat slopes in the rest-IR, ruling out a contribution from hot (Trsim500 K) dust. Similarly, FIR non-detections rule out any appreciable cold (T\lesssim75 K) dust component. Assuming energy balance, these observations are inconsistent with the typical FIR dust emission of dusty starbursts and quasar torii, which usually show a mixture of cold and hot dust. Additionally, our [\mathrmC_II] non-detections rule out typical dusty starbursts. We compute empirical maximum IR SEDs and find that both LRDs must have \log(L_\mathrmIR/L_⊙) ≲12.2 at the 3σlevel. These limits are in tension with the predictions of rest-optical spectrophotometric fits, be they galaxy only, AGN only, or composite. It is unlikely that LRDs are highly dust-reddened intrinsically blue sources with a dust temperature distribution that conspires to avoid current observing facilities. Rather, we favor an intrinsically redder LRD SED model that alleviates the need for strong dust attenuation.

</ol>

2024

1. A&A

   

   Euclid preparation. XXXI. The effect of the variations in photometric passbands on photometric-redshift accuracy

   Euclid Collaboration, S. Paltani, J. Coupon, W. G. Hartley, A. Alvarez-Ayllon, and 195 more authors

   Astronomy & Astrophysics, Jan 2024

   Abs DOI

   The technique of photometric redshifts has become essential for the exploitation of multi-band extragalactic surveys. While the requirements on photometric redshifts for the study of galaxy evolution mostly pertain to the precision and to the fraction of outliers, the most stringent requirement in their use in cosmology is on the accuracy, with a level of bias at the sub- percent level for the Euclid cosmology mission. A separate, and challenging, calibration process is needed to control the bias at this level of accuracy. The bias in photometric redshifts has several distinct origins that may not always be easily overcome. We identify here one source of bias linked to the spatial or time variability of the passbands used to determine the photometric colours of galaxies. We first quantified the effect as observed on several well-known photometric cameras, and found in particular that, due to the properties of optical filters, the redshifts of off-axis sources are usually overestimated. We show using simple simulations that the detailed and complex changes in the shape can be mostly ignored and that it is sufficient to know the mean wavelength of the passbands of each photometric observation to correct almost exactly for this bias; the key point is that this mean wavelength is independent of the spectral energy distribution of the source. We use this property to propose a correction that can be computationally efficiently implemented in some photometric-redshift algorithms, in particular template-fitting. We verified that our algorithm, implemented in the new photometric-redshift code Phosphoros, can effectively reduce the bias in photometric redshifts on real data using the CFHTLS T007 survey, with an average measured bias \ensuremath∆z over the redshift range 0.4 \ensuremath≤ z \ensuremath≤ 0.7 decreasing by about 0.02, specifically from \ensuremath∆z ≃ 0.04 to \ensuremath∆z ≃ 0.02 around z = 0.5. Our algorithm is also able to produce corrected photometry for other applications.

2. ApJ

   

   UNCOVER: JWST Spectroscopy of Three Cold Brown Dwarfs at Kiloparsec-scale Distances

   Adam J. Burgasser, Rachel Bezanson, Ivo Labbe, Gabriel Brammer, Sam E. Cutler, and 17 more authors

   The Astrophysical Journal, Feb 2024

   Abs DOI

   We report JWST/NIRSpec spectra of three distant T-type brown dwarfs identified in the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) survey of the Abell 2744 lensing field. One source was previously reported as a candidate T dwarf on the basis of NIRCam photometry, while two sources were initially identified as candidate active galactic nuclei. Low-resolution 1–5 \ensuremathμm spectra confirm the presence of molecular features consistent with T dwarf atmospheres, and comparison to spectral standards infers classifications of sdT1, T6, and T8–T9. The warmest source, UNCOVER-BD-1, shows evidence of subsolar metallicity, and atmosphere model fits indicate T _eff = 1300 K and [M/H] \ensuremath∼ ‑1.0, making this one of the few spectroscopically confirmed T subdwarfs known. The coldest source, UNCOVER-BD-3, is near the T/Y dwarf boundary with T _eff = 550 K, and our analysis indicates the presence of PH_3 in the 3–5 \ensuremathμm region, favored over CO_2 and a possible indicator of subsolar metallicity. We estimate distances of 0.9–4.5 kpc from the Galactic midplane, making these the most distant brown dwarfs with spectroscopic confirmation. Population simulations indicate high probabilities of membership in the Galactic thick disk for two of these brown dwarfs, and potential halo membership for UNCOVER-BD-1. Our simulations indicate that there are approximately 5 T dwarfs and 1–2 L dwarfs in the Abell 2744 field down to F444W = 30 AB mag, roughly one-third of which are thick disk members. These results highlight the utility of deep JWST/NIRSpec spectroscopy for identifying and characterizing the oldest metal-poor brown dwarfs in the Milky Way.

3. ApJ

   

   Quantifying the Effects of Known Unknowns on Inferred High-redshift Galaxy Properties: Burstiness, IMF, and Nebular Physics

   Bingjie Wang, Joel Leja, Hakim Atek, Ivo Labbé, Yijia Li, and 13 more authors

   The Astrophysical Journal, Mar 2024

   Abs DOI

   The era of the James Webb Space Telescope ushers stellar population models into uncharted territories, particularly at the high- redshift frontier. In a companion paper, we apply the Prospector Bayesian framework to jointly infer galaxy redshifts and stellar population properties from broadband photometry as part of the UNCOVER survey. Here we present a comprehensive error budget in spectral energy distribution (SED) modeling. Using a sample selected to have photometric redshifts higher than 9, we quantify the systematic shifts stemming from various model choices in inferred stellar mass, star formation rate (SFR), and age. These choices encompass different timescales for changes in the star formation history (SFH), nonuniversal stellar initial mass functions (IMF), and the inclusion of variable nebular abundances, gas density, and ionizing photon budget. We find that the IMF exerts the strongest influence on the inferred properties: the systematic uncertainties can be as much as 1 dex, 2–5 times larger than the formal reported uncertainties in mass and SFR, and importantly, exceed the scatter seen when using different SED fitting codes. Although the assumptions on the lower end of the IMF induce degeneracy, our findings suggest that a common practice in the literature of assessing uncertainties in SED-fitting processes by comparing multiple codes is substantively underestimating the true systematic uncertainty. Highly stochastic SFHs change the inferred SFH by much larger than the formal uncertainties, and introduce \ensuremath∼0.8 dex systematics in SFR averaged over a short timescale and \ensuremath∼0.3 dex systematics in average age. Finally, employing a flexible nebular emission model causes \ensuremath∼0.2 dex systematic increase in mass and SFR, comparable to the formal uncertainty. This paper constitutes an initial step toward a complete uncertainty estimate in SED modeling.

4. ApJ

   UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5

   Jenny E. Greene, Ivo Labbe, Andy D. Goulding, Lukas J. Furtak, Iryna Chemerynska, and 31 more authors

   The Astrophysical Journal, Mar 2024

   Abs DOI

   The James Webb Space Telescope is revealing a new population of dust- reddened broad-line active galactic nuclei (AGN) at redshifts z \ensuremath≳ 5. Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) of 15 AGN candidates selected to be compact, with red continua in the rest-frame optical but with blue slopes in the UV. From NIRCam photometry alone, they could have been dominated by dusty star formation or an AGN. Here we show that the majority of the compact red sources in UNCOVER are dust-reddened AGN: 60% show definitive evidence for broad-line H\ensuremathα with a FWHM > 2000 km s ^‑1, 20% of the current data are inconclusive, and 20% are brown dwarf stars. We propose an updated photometric criterion to select red z > 5 AGN that excludes brown dwarfs and is expected to yield >80% AGN. Remarkably, among all z _phot > 5 galaxies with F277W – F444W > 1 in UNCOVER at least 33% are AGN regardless of compactness, climbing to at least 80% AGN for sources with F277W – F444W > 1.6. The confirmed AGN have black hole masses of 10^7–10^9 M _\ensuremath⊙. While their UV luminosities (‑16 > M _UV > ‑20 AB mag) are low compared to UV-selected AGN at these epochs, consistent with percent-level scattered AGN light or low levels of unobscured star formation, the inferred bolometric luminosities are typical of 10^7–10^9 M _\ensuremath⊙ black holes radiating at \ensuremath∼10%–40% the Eddington limit. The number densities are surprisingly high at \ensuremath∼10^‑5 Mpc^‑3 mag^‑1, 100 times more common than the faintest UV-selected quasars, while accounting for \ensuremath∼1% of the UV-selected galaxies. While their UV faintness suggests they may not contribute strongly to reionization, their ubiquity poses challenges to models of black hole growth.

5. ApJ

   

   Size–Stellar Mass Relation and Morphology of Quiescent Galaxies at z ≥ 3 in Public JWST Fields

   Kei Ito, Francesco Valentino, Gabriel Brammer, Andreas L. Faisst, Steven Gillman, and 17 more authors

   The Astrophysical Journal, Apr 2024

   Abs DOI

   We present the results of a systematic study of the rest-frame optical morphology of quiescent galaxies at z \ensuremath≥ 3 using the Near-Infrared Camera (NIRCam) on board the James Webb Space Telescope (JWST). Based on a sample selected by UVJ color or NUVUVJ color, we focus on 26 quiescent galaxies with 9.8 \mathrmlog(M_⋆/M_⊙) 11.4 at 2.8 < z _phot < 4.6 with publicly available JWST data. Their sizes are constrained by fitting the Sérsic profile to all available NIRCam images. We see a negative correlation between the observed wavelength and the size and derive their size at the rest frame 0.5 \ensuremathμm using size measurements in multiple bands. Our quiescent galaxies show a significant correlation between the rest-frame 0.5 \ensuremathμm size and the stellar mass at z \ensuremath≥ 3. The analytical fit for them at \mathrmlog(M_⋆/M_⊙) 10.3 implies that our size–stellar mass relations are below those at lower redshifts, with the amplitude of \ensuremath∼0.6 kpc at M _\ensuremath⋆ = 5 \texttimes 10^10 M _\ensuremath⊙. This value agrees with the extrapolation of the size evolution of quiescent galaxies at z < 3 in the literature, implying that the size of quiescent galaxies increases monotonically from z \ensuremath∼ 3–5. Our sample mainly comprises galaxies with bulge-like structures according to their median Sérsic index and axis ratio of n \ensuremath∼ 3–4 and q \ensuremath∼ 0.6–0.8, respectively. On the other hand, there is a trend of increasing fraction of galaxies with low Sérsic index at higher redshift, suggesting 3 < z < 5 might be the epoch of onset of morphological transformation with a fraction of very notable disky quenched galaxies.

6. ApJL

   Remarkably Compact Quiescent Candidates at 3 < z < 5 in JWST-CEERS

   Lillian Wright, Katherine E. Whitaker, John R. Weaver, Sam E. Cutler, Bingjie Wang, and 7 more authors

   The Astrophysical Journal Letters, Mar 2024

   Abs DOI

   In this Letter, we measure the rest-frame optical and near-infrared sizes of 10 quiescent candidates at 3 < z < 5, first reported by Carnall et al. We use James Webb Space Telescope Near-Infrared Camera F277W and F444W imaging obtained through the public CEERS Early Release Science program and imcascade, an astronomical fitting code that utilizes multi-Gaussian expansion, to carry out our size measurements. When compared to the extrapolation of rest-optical size–mass relations for quiescent galaxies at lower redshift, 8 out of 10 candidates in our sample (80%) are on average more compact by \ensuremath∼40%. A total of 7 out of 10 candidates (70%) exhibit rest-frame infrared sizes \ensuremath∼10% smaller than rest-frame optical sizes, indicative of negative color gradients. Two candidates (20%) have rest-frame infrared sizes \ensuremath∼1.4\texttimes larger than rest-frame optical sizes; one of these candidates exhibits signs of ongoing or residual star formation, suggesting this galaxy may not be fully quenched. The remaining candidate is unresolved in both filters, which may indicate an active galactic nucleus. Strikingly, we observe three of the most massive galaxies in the sample (log(M _\ensuremath⋆/M _\ensuremath⊙) = 10.74–10.95) are extremely compact, with effective radii \ensuremath∼0.7 kpc. Our findings provide no indication that the size evolution relation flattens out, and may indicate that the size evolution of quiescent galaxies is steeper than previously anticipated beyond z > 3.

7. ApJ

   

   COSMOS-Web: Intrinsically Luminous z ≳ 10 Galaxy Candidates Test Early Stellar Mass Assembly

   Caitlin M. Casey, Hollis B. Akins, Marko Shuntov, Olivier Ilbert, Louise Paquereau, and 37 more authors

   The Astrophysical Journal, Apr 2024

   Abs DOI

   We report the discovery of 15 exceptionally luminous 10 \ensuremath≲ z \ensuremath≲ 14 candidate galaxies discovered in the first 0.28 deg^2 of JWST/NIRCam imaging from the COSMOS-Web survey. These sources span rest- frame UV magnitudes of ‑20.5 > M _UV > ‑22, and thus constitute the most intrinsically luminous z \ensuremath≳ 10 candidates identified by JWST to date. Selected via NIRCam imaging, deep ground-based observations corroborate their detection and help significantly constrain their photometric redshifts. We analyze their spectral energy distributions using multiple open-source codes and evaluate the probability of low-redshift solutions; we conclude that 12/15 (80%) are likely genuine z \ensuremath≳ 10 sources and 3/15 (20%) likely low-redshift contaminants. Three of our z \ensuremath∼ 12 candidates push the limits of early stellar mass assembly: they have estimated stellar masses \ensuremath∼ 5 \texttimes 10^9 M _\ensuremath⊙, implying an effective stellar baryon fraction of ϵ _\ensuremath⋆ \ensuremath∼ 0.2‑0.5, where ϵ _\ensuremath⋆ \ensuremath≡ M _\ensuremath⋆/(f _ b M _halo). The assembly of such stellar reservoirs is made possible due to rapid, burst-driven star formation on timescales < 100 Myr where the star formation rate may far outpace the growth of the underlying dark matter halos. This is supported by the similar volume densities inferred for M _\ensuremath⋆ \ensuremath∼ 10^10 M _\ensuremath⊙ galaxies relative to M _\ensuremath⋆ \ensuremath∼ 10^9 M _\ensuremath⊙—both about 10^‑6 Mpc^‑3—implying they live in halos of comparable mass. At such high redshifts, the duty cycle for starbursts would be of order unity, which could cause the observed change in the shape of the UV luminosity function from a double power law to a Schechter function at z \ensuremath≈ 8. Spectroscopic redshift confirmation and ensuing constraints of their masses will be critical to understand how, and if, such early massive galaxies push the limits of galaxy formation in the Lambda cold dark matter paradigm.

8. ApJ

   

   Large-scale Structures in COSMOS2020: Evolution of Star Formation Activity in Different Environments at 0.4 < z < 4

   Sina Taamoli, Bahram Mobasher, Nima Chartab, Behnam Darvish, John R. Weaver, and 13 more authors

   The Astrophysical Journal, May 2024

   Abs DOI

   To study the role of environment in galaxy evolution, we reconstruct the underlying density field of galaxies based on COSMOS2020 (The Farmer catalog) and provide the density catalog for a magnitude- limited (K _ s < 24.5) sample of \ensuremath∼210,000 galaxies at 0.4 < z < 5 within the COSMOS field. The environmental densities are calculated using a weighted kernel density estimation approach with the choice of a von Mises–Fisher kernel, an analog of the Gaussian kernel for periodic data. Additionally, we make corrections for the edge effect and masked regions in the field. We utilize physical properties extracted by LePhare to investigate the connection between star formation activity and the environmental density of galaxies in six mass-complete subsamples at different cosmic epochs within 0.4 < z < 4. Our findings confirm a strong anticorrelation between star formation rate (SFR)/specific SFR (sSFR) and environmental density out to z \ensuremath∼ 1.1. At 1.1 < z < 2, there is no significant correlation between SFR/sSFR and density. At 2 < z < 4, we observe a reversal of the SFR/sSFR–density relation such that both SFR and sSFR increase by a factor of \ensuremath∼10 with increasing density contrast, \ensuremathδ, from ‑0.4 to 5. This observed reversal at higher redshifts supports the scenario where an increased availability of gas supply, along with tidal interactions and a generally higher star formation efficiency in dense environments, could potentially enhance star formation activity in galaxies located in rich environments at z > 2.

9. ApJL

   

   Two Distinct Classes of Quiescent Galaxies at Cosmic Noon Revealed by JWST PRIMER and UNCOVER

   Sam E. Cutler, Katherine E. Whitaker, John R. Weaver, Bingjie Wang, Richard Pan, and 29 more authors

   The Astrophysical Journal Letters, Jun 2024

   Abs DOI

   We present a measurement of the low-mass quiescent size–mass relation at cosmic noon (1 < z < 3) from the JWST PRIMER and UNCOVER treasury surveys, which highlights two distinct classes of quiescent galaxies. While the massive population is well studied at these redshifts, the low-mass end has been previously underexplored due to a lack of observing facilities with sufficient sensitivity and spatial resolution. We select a conservative sample of low-mass quiescent galaxy candidates using rest-frame UVJ colors and specific star formation rate criteria and measure galaxy morphology in both rest-frame UV/optical wavelengths (F150W) and rest-frame near-infrared (F444W). We confirm an unambiguous flattening of the low-mass quiescent size–mass relation, which results from the separation of the quiescent galaxy sample into two distinct populations at \mathrmlog(M_⋆/M_⊙)∼10.3 : low-mass quiescent galaxies that are notably younger and have disky structures, and massive galaxies consistent with spheroidal morphologies and older median stellar ages. These separate populations imply mass quenching dominates at the massive end while other mechanisms, such as environmental or feedback-driven quenching, form the low-mass end. This stellar mass-dependent slope of the quiescent size–mass relation could also indicate a shift from size growth due to star formation (low masses) to growth via mergers (massive galaxies). The transition mass between these two populations also corresponds with other dramatic changes and characteristic masses in several galaxy evolution scaling relations (e.g., star formation efficiency, dust obscuration, and stellar-to-halo mass ratios), further highlighting the stark dichotomy between low- mass and massive galaxy formation.

10. ApJ

    

    The Web Epoch of Reionization Lyα Survey (WERLS). I. MOSFIRE Spectroscopy of z ∼ 7–8 Lyα Emitters

    Olivia R. Cooper, Caitlin M. Casey, Hollis B. Akins, Jake Magee, Alfonso Melendez, and 32 more authors

    The Astrophysical Journal, Jul 2024

    Abs DOI

    We present the first results from the Web Epoch of Reionization Ly\ensuremathα Survey (WERLS), a spectroscopic survey of Ly\ensuremathα emission using Keck I/MOSFIRE and LRIS. WERLS targets bright (J < 26) galaxy candidates with photometric redshifts of 5.5 \ensuremath≲ z \ensuremath≲ 8 selected from pre-JWST imaging embedded in the Epoch of Reionization (EoR) within three JWST deep fields: CEERS, PRIMER, and COSMOS-Web. Here, we report 11 z \ensuremath∼ 7–8 Ly\ensuremathα emitters (LAEs; three secure and eight tentative candidates) detected in the first five nights of WERLS MOSFIRE data. We estimate our observed LAE yield is \ensuremath∼13%, which is broadly consistent with expectations assuming some loss from redshift uncertainty, contamination from sky OH lines, and that the Universe is approximately half-ionized at this epoch, whereby observable Ly\ensuremathα emission is unlikely for galaxies embedded in a neutral intergalactic medium. Our targets are selected to be UV-bright, and span a range of absolute UV magnitudes with ‑23.1 < M _UV < ‑19.8. With two LAEs detected at z = 7.68, we also consider the possibility of an ionized bubble at this redshift. Future synergistic Keck+JWST efforts will provide a powerful tool for pinpointing beacons of reionization and mapping the large-scale distribution of mass relative to the ionization state of the Universe. *The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

11. ApJ

    

    3D-DASH: The Evolution of Size, Shape, and Intrinsic Scatter in Populations of Young and Old Quiescent Galaxies at 0.5 < z < 3

    Maike Clausen, Katherine E. Whitaker, Ivelina Momcheva, Sam E. Cutler, Katherine A. Suess, and 11 more authors

    The Astrophysical Journal, Aug 2024

    Abs DOI

    We present a study of the growth of the quiescent galaxy population between 0.5 < z < 3 by tracing the number density and structural evolution of a sample of 4518 old and 583 young quiescent galaxies with log(M _\ensuremath⋆/M _\ensuremath⊙) > 10.4, selected from the COSMOS2020 catalog with complementary Hubble Space Telescope F160W imaging from the 3D-DASH survey. Among the quiescent population at z \ensuremath∼ 2, roughly 50% are recently quenched galaxies; these young quiescent galaxies become increasingly rare toward lower redshift, supporting the idea that the peak epoch of massive galaxy quenching occurred at z > 2. Our data show that while the effective half-light radius of quiescent galaxies generally increases with time, young quiescent galaxies are significantly smaller than their older counterparts at the same redshift. In this work we investigate the connection between this size difference and other structural properties, including axis ratio, color gradients, stellar mass, and the intrinsic scatter in effective radius. We demonstrate that the size difference is driven by the most massive subpopulation (log(M _\ensuremath⋆/M _\ensuremath⊙) > 11) and does not persist when restricting the sample to intermediate-mass galaxies (10.4 < log(M _\ensuremath⋆/M _\ensuremath⊙) < 11). Interestingly, the intrinsic scatter in physical size shows a strong coevolution over the investigated time period and peaks around z \ensuremath∼ 2 for both populations, only diverging at z < 1. Taken together, and assuming we are not missing a significant population of lower surface brightness galaxies, while the formation and quenching mechanisms that dominate at higher redshifts yield compact remnants, multiple evolutionary pathways may explain the diverse morphologies of galaxies that quench at z < 1.

12. ApJ

    The JWST UNCOVER Treasury Survey: Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization

    Rachel Bezanson, Ivo Labbe, Katherine E. Whitaker, Joel Leja, Sedona H. Price, and 38 more authors

    The Astrophysical Journal, Oct 2024

    Abs DOI

    In this paper we describe the survey design for the Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) Cycle 1 JWST Treasury program, which executed its early imaging component in 2022 November. The UNCOVER survey includes ultradeep (\ensuremath∼29–30AB) imaging of \ensuremath∼45 arcmin^2 on and around the well-studied A2744 galaxy cluster at z = 0.308 and will follow up \ensuremath∼500 galaxies with extremely deep low- resolution spectroscopy with the NIRSpec/PRISM during the summer of 2023, with repeat visits in summer 2024. We describe the science goals, survey design, target selection, and planned data releases. We also present and characterize the depths of the first NIRCam imaging mosaic, highlighting previously unparalleled resolved and ultradeep 2–4 \ensuremathμm imaging of known objects in the field. The UNCOVER primary NIRCam mosaic spans 28.8 arcmin^2 in seven filters (F115W, F150W, F200W, F277W, F356W, F410M, and F444W) and 16.8 arcmin^2 in our NIRISS parallel (F115W, F150W, F200W, F356W, and F444W). To maximize early community use of the Treasury data set, we publicly release the full reduced mosaics of public JWST imaging including 45 arcmin^2 NIRCam and 17 arcmin^2 NIRISS mosaics on and around the A2744 cluster, including the Hubble Frontier Field primary and parallel footprints.

13. ApJ

    UNCOVER NIRSpec/PRISM Spectroscopy Unveils Evidence of Early Core Formation in a Massive, Centrally Dusty Quiescent Galaxy at z _spec = 3.97

    David J. Setton, Gourav Khullar, Tim B. Miller, Rachel Bezanson, Jenny E. Greene, and 26 more authors

    The Astrophysical Journal, Oct 2024

    Abs DOI

    We report the spectroscopic confirmation of a massive ( <mml:math overflow=“scroll”>log<mml:mo stretc hy=“false”>(</mml:mo>M</m ml:mrow>\ensuremath⋆</mml:mro w></mml:msub><mml:mo stretchy=“true”>/</mml:mo></mml :mrow>M\ensuremath⊙<mml :mo stretchy=“false”>)</mml:mo>=10.34 \ensuremath\pm</mml: mo></mml:mrow>0.070.06</mml:mrow></mml:msubsup></mml:math> </inline-formula>), Hubble Space Telescope–dark (m _F150W ‑ m _F444W = 3.6) quiescent galaxy at z _spec = 3.97 in the UNCOVER survey. NIRSpec/PRISM spectroscopy and a nondetection in deep Atacama Large Millimeter/submillimeter Array imaging surprisingly reveals that the galaxy is consistent with a low (<10 M _\ensuremath⊙ yr^‑1) star formation rate (SFR) despite evidence for moderate dust attenuation. The F444W image is well modeled with a two- component Sérsic fit that favors a compact, r _ e \ensuremath∼ 200 pc, n \ensuremath∼ 2.9 component and a more extended, r _ e \ensuremath∼ 1.6 kpc, n \ensuremath∼ 1.7 component. The galaxy exhibits strong color gradients: the inner regions are significantly redder than the outskirts. Spectral energy distribution models that reproduce both the red colors and low SFR in the center of UNCOVER 18407 require both significant (A _ v \ensuremath∼ 1.4 mag) dust attenuation and a stellar mass-weighted age of 900 Myr, implying 50% of the stars in the core already formed by z = 7.5. Using spatially resolved annular mass-to-light measurements enabled by the galaxy’s moderate magnification ( <mml:math overflow=“scroll”>\ensuremathμ</mml:mi>=2.12< /mml:mn>\ensuremath\pm</mml:m o></mml:mrow>0.010.05</mml:msubsup></mml:math> </inline-formula>) to reconstruct a radial mass profile from the best-fitting two-component Sérsic model, we infer a total mass-weighted <mml:math overflow=“scroll”>r eff</mml:msub>=0.74 \ensuremath\pm</mml: mo></mml:mrow>0.170.22</mml:mrow></mml:msubsup></mml:math> </inline-formula> kpc and log <mml:math overflow=“scroll”><mml:mo stretchy=“false”>(</mml:mo><mml:mi mathvariant=“nor mal”>\ensuremathΣ</mml:mi>1 <mml:mspace width=“0.33em”></mml:mspace>kpc</ mml:mrow></mml:msub><mml:mspace width=“0.33em”></mml:mspace><mml:mo stretchy=“false”>[</mml: mo>M\ensuremath⊙</mml :mo></mml:msub><mml:mspace width=“0.25em”></mml:mspace>kpc-2</mm l:mn></mml:mrow></mml:msup><mml:mo stretchy=“false”>]</mml:mo><mml:mo stretchy=“false”>)</mml:m o>=9.65\ ensuremath\pm0.150.12</mml: mn></mml:msubsup></mml:math> </inline-formula>. The early formation of a dense, low SFR, and dusty core embedded in a less attenuated stellar envelope suggests an evolutionary link between the earliest-forming massive galaxies and their elliptical descendants. Furthermore, the disparity between the global, integrated dust properties and the spatially resolved gradients highlights the importance of accounting for radially varying stellar populations when characterizing the early growth of galaxy structure.</p> </div> </div> </div> </li>

14. ApJL

    

    JWST Reveals Bulge-dominated Star-forming Galaxies at Cosmic Noon

    Chloë E. Benton, Erica J. Nelson, Tim B. Miller, Rachel Bezanson, Justus Gibson, and 8 more authors

    The Astrophysical Journal Letters, Oct 2024

    Abs DOI

    Hubble Space Telescope imaging shows that most star-forming galaxies at cosmic noon—the peak of cosmic star formation history—appear disk-dominated, leaving the origin of the dense cores in their quiescent descendants unclear. With the James Webb Space Telescope’s high-resolution imaging to 5 \ensuremathμm, we can now map the rest-frame near-infrared emission, a much closer proxy for stellar mass distribution, in these massive galaxies. We selected 70 star-forming galaxies with 10 < log(M) < 12 and 1.5 < z < 3 in the CEERS survey and compare their morphologies in the rest-frame optical to those in the rest-frame near-IR. While the bulk of these galaxies are disk-dominated in 1.5 \ensuremathμm (rest-frame optical) imaging, they appear more bulge-dominated at 4.4 \ensuremathμm (rest-frame near-infrared). Our analysis reveals that in massive star-forming galaxies at z \ensuremath∼ 2, the radial surface brightness profiles steepen significantly, from a slope of \ensuremath∼0.3 dex^‑1 at 1.5 \ensuremathμm to \ensuremath∼1.4 dex^‑1 at 4.4 \ensuremathμm within radii <1 kpc. Additionally, we find their total flux contained within the central 1 kpc is approximately 7 times higher in F444W than in F150W. In rest-optical emission, a galaxy’s central surface density appears to be the strongest indicator of whether it is quenched or star-forming. Our most significant finding is that at redder wavelengths, the central surface density ratio between quiescent and star-forming galaxies dramatically decreases from \ensuremath∼10 to \ensuremath∼1. This suggests the high central densities associated with galaxy quenching are already in place during the star-forming phase, imposing new constraints on the transition from star formation to quiescence.

15. ApJ

    

    Medium Bands, Mega Science: A JWST/NIRCam Medium-band Imaging Survey of A2744

    Katherine A. Suess, John R. Weaver, Sedona H. Price, Richard Pan, Bingjie Wang, and 38 more authors

    The Astrophysical Journal, Nov 2024

    Abs DOI

    In this paper, we describe the “Medium Bands, Mega Science” JWST Cycle 2 survey (JWST-GO-4111) and demonstrate the power of these data to reveal both the spatially integrated and spatially resolved properties of galaxies from the local Universe to the era of cosmic dawn. Executed in 2023 November, MegaScience obtained \ensuremath∼30 arcmin^2 of deep multiband NIRCam imaging centered on the z \ensuremath∼ 0.3 A2744 cluster, including 11 medium-band filters and the two shortest-wavelength broadband filters, F070W and F090W. Together, MegaScience and the UNCOVER Cycle 1 treasury program provide a complete set of deep (\ensuremath∼28–30 mag_AB) images in all NIRCam medium- and broadband filters. This unique data set allows us to precisely constrain photometric redshifts, map stellar populations and dust attenuation for large samples of distant galaxies, and examine the connection between galaxy structures and formation histories. MegaScience also includes \ensuremath∼17 arcmin^2 of NIRISS parallel imaging in two broadband and four medium-band filters from 0.9 to 4.8 \ensuremathμm, expanding the footprint where robust spectral energy distribution (SED) fitting is possible. We provide example SEDs and multiband cutouts at a variety of redshifts, and use a catalog of JWST spectroscopic redshifts to show that MegaScience improves both the scatter and catastrophic outlier rate of photometric redshifts by factors of 2–3. Additionally, we demonstrate the spatially resolved science enabled by MegaScience by presenting maps of the [O III] line emission and continuum emission in three spectroscopically confirmed z > 6 galaxies. We show that line emission in reionization-era galaxies can be clumpy, extended, and spatially offset from continuum emission, implying that galaxy assembly histories are complex even at these early epochs. We publicly release fully reduced mosaics and photometric catalogs for both the NIRCam primary and NIRISS parallel fields (jwst-uncover.github.io/megascience).

16. ApJL

    

    The Extreme Low-mass End of the Mass–Metallicity Relation at z ∼ 7

    Iryna Chemerynska, Hakim Atek, Pratika Dayal, Lukas J. Furtak, Robert Feldmann, and 15 more authors

    The Astrophysical Journal Letters, Nov 2024

    Abs DOI

    The mass–metallicity relation provides crucial insights into the baryon cycle in galaxies and strong constraints on galaxy formation models. We use JWST NIRSpec observations from the UNCOVER program to measure the gas-phase metallicity in a sample of eight galaxies during the epoch of reionization at z = 6–8. Thanks to the strong lensing of the galaxy cluster Abell 2744, we are able to probe extremely low stellar masses between 10^6 and 10^8 M _\ensuremath⊙. Using strong-line diagnostics and the most recent JWST calibrations, we derive extremely low oxygen abundances in the range of 12 + log(O/H) = 6.7–7.8. By combining this sample with more massive galaxies at similar redshifts, we derive a best-fit relation of 12 + log(O/H) = <mml:math overflow=“scroll”>‑0.076‑0.03</mml:mrow>< mml:mo>+</mml:mo>0.03</mml:msubsup>< mml:mo>\texttimes</mml:mo><mml:mo stretchy=“false”>(</mml:mo>log<mml:mo stretch y=“false”>(</mml:mo>M</mm l:mrow>\ensuremath⋆</mml:msub><mml:mo stretchy=“false”>)</mml:mo><mml:mo stretch y=“false”>)</mml:mo>2</m ml:mrow></mml:msup>+<mml :mn>1.61</mml:mn>‑ 0.52+0.52 </mml:math> </inline-formula> \texttimes <mml:math overflow=“scroll”>log<mml:mo stretchy=“false ”>(</mml:mo>M\ensuremath⋆</mml:mrow></mml:ms ub><mml:mo stretchy=“false”>)</mml:mo>‑0.26<mml: mo>‑</mml:mo>0.10+ 0.10</mml:msubsup></mml:mat h> </inline-formula>, which becomes steeper than determinations at z \ensuremath∼ 3–6 toward low-mass galaxies. Our results show a clear redshift evolution in the overall normalization of the relation, galaxies at higher redshift having significantly lower metallicities at a given mass. A comparison with theoretical models provides important constraints on which physical processes, such as metal mixing, star formation or feedback recipes, are important in reproducing the observations. Additionally, these galaxies exhibit star formation rates that are higher by a factor of a few to tens compared to extrapolated relations at similar redshifts or theoretical predictions of main-sequence galaxies, pointing to a recent burst of star formation. All these observations are indicative of the highly stochastic star formation and interstellar medium enrichment expected in these low-mass systems, suggesting that feedback mechanisms in high-z dwarf galaxies might be different from those in place at higher masses.</p> </div> </div> </div> </li>

17. ApJ

    

    UNCOVER: A NIRSpec Census of Lensed Galaxies at z = 8.50–13.08 Probing a High-AGN Fraction and Ionized Bubbles in the Shadow

    Seiji Fujimoto, Bingjie Wang, John R. Weaver, Vasily Kokorev, Hakim Atek, and 31 more authors

    The Astrophysical Journal, Dec 2024

    Abs DOI

    We present JWST NIRSpec prism spectroscopy of lensed galaxies at z \ensuremath≳ 9 found behind the massive galaxy cluster Abell 2744 in the UNCOVER Cycle 1 Treasury Program. We confirm the redshift via emission lines and/or the Ly\ensuremathα break for 10 galaxies at z = 8.50–13.08 down to M _ V = ‑17.3. We achieve a 100% confirmation rate for z > 9 candidates reported in H. Atek et al. Using six sources with multiple line detections, we find that offsets in redshift estimates between the lines and the Ly\ensuremathα break alone can be \ensuremath\pm0.2, raising caution in designing future follow-up spectroscopy for the break-only sources with the Atacama Large Millimeter/submillimeter Array. With spec-z- confirmed sources in UNCOVER and the literature, we derive lower limits on the rest-frame ultraviolet (UV) luminosity function (LF) at z ≃ 9–12 and find that these lower limits agree with recent photometric measurements. We identify at least two unambiguous and several possible active galactic nucleus (AGN) systems based on X-ray, broad H\ensuremathβ, high ionization lines, and excess in the UV LF. This requires the AGN LFs at z ≃ 9–10 to be comparable or even higher than the X-ray AGN LF estimated at z \ensuremath∼ 6 and suggests a plausible cause of the high abundance of z > 9 galaxies claimed in the recent photometric measurements is AGNs. One UV-luminous source is confirmed at the same redshift as a broad-line AGN at z = 8.50 with a physical separation of 380 kpc in the source plane. These two sources show emission blueward of Ly\ensuremathα, indicating a giant ionized bubble enclosing them with a radius of 7.69 \ensuremath\pm 0.18 pMpc. Our results imply that AGNs have a nonnegligible contribution to cosmic reionization.

18. ApJ

    

    COSMOS2020: Disentangling the Role of Mass and Environment in Star Formation Activity of Galaxies at 0.4 < z < 4

    Sina Taamoli, Negin Nezhad, Bahram Mobasher, Faezeh Manesh, Nima Chartab, and 12 more authors

    The Astrophysical Journal, Dec 2024

    Abs DOI

    The role of internal and environmental factors in the star formation activity of galaxies is still a matter of debate, in particular at higher redshifts. Leveraging the most recent release of the COSMOS catalog, COSMOS2020, as well as density measurements from our previous study, we disentangle the impact of environment and stellar mass on the star formation rate (SFR) and specific SFR (sSFR) of a sample of \ensuremath∼210,000 galaxies within a redshift range of 0.4 < z < 4, and present our findings in three cosmic epochs: (1) out to z \ensuremath∼ 1, the average SFR and sSFR decline in extremely dense environments and at the high-mass end of the distribution, which is mostly due to the presence of the massive quiescent population; (2) at 1 < z < 2, the environmental dependence diminishes, while mass is still the dominant factor in star formation activity; and (3) beyond z \ensuremath∼ 2, our sample is dominated by star-forming galaxies and we observe a reversal of the trends seen in the local Universe—the average SFR increases with increasing environmental density. Our analysis shows that both environmental and mass quenching efficiencies increase with stellar mass at all redshifts, with mass being the dominant quenching factor in massive galaxies compared to environmental effects. At 2 < z < 4, negative values of environmental quenching efficiency suggest that the fraction of star-forming galaxies in dense environments exceeds that in less-dense regions, likely due to the greater availability of cold gas, higher merger rates, and tidal effects that trigger star formation activity.

19. ApJS

    

    The UNCOVER Survey: A First-look HST + JWST Catalog of 60,000 Galaxies near A2744 and beyond

    John R. Weaver, Sam E. Cutler, Richard Pan, Katherine E. Whitaker, Ivo Labbé, and 41 more authors

    The Astrophysical Journal Supplement Series, Jan 2024

    Abs DOI

    In 2022 November, the James Webb Space Telescope (JWST) returned deep near-infrared images of A2744-a powerful lensing cluster capable of magnifying distant, incipient galaxies beyond it. Together with existing Hubble Space Telescope (HST) imaging, this publicly available data set opens a fundamentally new discovery space to understand the remaining mysteries of the formation and evolution of galaxies across cosmic time. In this work, we detect and measure some 60,000 objects across the 49 arcmin^2 JWST footprint down to a 5\ensuremathσ limiting magnitude of \raisebox-0.5ex\textasciitilde30 mag in 0.″32 apertures. Photometry is performed using circular apertures on images matched to the point-spread function (PSF) of the reddest NIRCam broad band, F444W, and cleaned of bright cluster galaxies and the related intracluster light. To give an impression of the photometric performance, we measure photometric redshifts and achieve a \ensuremathσ _NMAD \ensuremath≈ 0.03 based on known, but relatively small, spectroscopic samples. With this paper, we publicly release our HST and JWST PSF-matched photometric catalog with optimally assigned aperture sizes for easy use, along with single aperture catalogs, photometric redshifts, rest-frame colors, and individual magnification estimates. These catalogs will set the stage for efficient and deep spectroscopic follow up of some of the first JWST-selected samples in summer of 2023.

20. ApJS

    

    The UNCOVER Survey: A First-look HST+JWST Catalog of Galaxy Redshifts and Stellar Population Properties Spanning 0.2 ≲ z ≲ 15

    Bingjie Wang, Joel Leja, Ivo Labbé, Rachel Bezanson, Katherine E. Whitaker, and 39 more authors

    The Astrophysical Journal Supplement Series, Jan 2024

    Abs DOI

    The recent UNCOVER survey with the James Webb Space Telescope (JWST) exploits the nearby cluster A2744 to create the deepest view of our Universe to date by leveraging strong gravitational lensing. In this work, we perform photometric fitting of more than 50,000 robustly detected sources out to z \raisebox-0.5ex~15. We show the redshift evolution of stellar ages, star formation rates, and rest-frame colors across the full range of 0.2 \ensuremath≲ z \ensuremath≲ 15. The galaxy properties are inferred using the Prospector Bayesian inference framework using informative Prospector-\ensuremathβ priors on the masses and star formation histories to produce joint redshift and stellar populations posteriors. Additionally, lensing magnification is performed on the fly to ensure consistency with the scale-dependent priors. We show that this approach produces excellent photometric redshifts with \ensuremathσ _NMAD \raisebox-0.5ex~0.03, of a similar quality to the established photometric redshift code EAzY. In line with the open-source scientific objective of this Treasury survey, we publicly release the stellar population catalog with this paper, derived from our photometric catalog adapting aperture sizes based on source profiles. This release (the catalog and all related documentation are accessible via the UNCOVER survey web page: https://jwst- uncover.github.io/DR2.html#SPSCatalogs with a copy deposited to Zenodo at doi:10.5281/zenodo.8401181) includes posterior moments, maximum likelihood spectra, star formation histories, and full posterior distributions, offering a rich data set to explore the processes governing galaxy formation and evolution over a parameter space now accessible by JWST.

21. ApJS

    

    Self-consistent Combined HST, K-band, and Spitzer Photometric Catalogs of the BUFFALO Survey Fields

    Amanda Pagul, F. Javier Sánchez, Iary Davidzon, Anton M. Koekemoer, Bahram Mobasher, and 12 more authors

    The Astrophysical Journal Supplement Series, Jul 2024

    Abs DOI

    This article presents new astronomical source catalogs using data from the BUFFALO Survey. These catalogs contain detailed information for over 100,000 astronomical sources in the six BUFFALO clusters: A370, A2744, AS1063, MACS 0416, MACS 0717, and MACS 1149 spanning a total of 240 arcmin^2. The catalogs include positions and forced photometry measurements of these objects in the F275W, F336W, F435W, F606W, F814W, F105W, F125W, F140W, and F160W HST bands, Keck-NIRC2/VLT-HAWKI Ks band, and IRAC Channel 1 and 2 bands. Additionally, we include photometry measurements in the F475W, F625W, and F110W bands for A370. This catalog also includes photometric redshift estimates computed via template fitting using LEPHARE. When comparing to a spectroscopic reference, we obtain an outlier fraction of 8.6% and scatter, normalized median absolute deviation, of 0.059. The catalogs are publicly available for their use by the community (https://archive.stsci.edu/hlsp/buffalo/).

22. arXiv

    UNCOVERing the contribution of black holes to reionization in the JWST era

    Pratika Dayal, Marta Volonteri, Jenny E. Greene, Vasily Kokorev, Andy D. Goulding, and 11 more authors

    arXiv, Jan 2024

    Abs DOI

    With its sensitivity in the rest-frame optical, the James Webb Space Telescope (JWST) has uncovered active galactic nuclei (AGN), comprising both intrinsically faint and heavily reddened sources, well into the first billion years of the Universe, at z ∼4-11. In this work, we revisit the AGN contribution to reionization given the high number densities associated with these objects. We use the DELPHI semi-analytic model, base-lined against the latest high-redshift datasets from the JWST and the Atacama Large millimetre Array (ALMA) to model early star forming galaxies and AGN. We calculate the escape fractions of ionizing radiation from both star formation and AGN and include the impact of reionization feeback in suppressing the baryonic content of low-mass galaxies in ionized regions. This model is validated against the key observables for star forming galaxy, AGN and reionization. In our {\textbackslashit fiducial} model, reionization reaches its mid-point at z ∼6.9 and ends by z ∼5.9. Low stellar mass (M_*≤10^9M_⊙) star forming galaxies are found to be the key drivers of the reionization process, providing about 77% of the total photon budget. Despite their high numbers, high accretion rates and higher escape fractions compared to star forming galaxies at z ∼5, AGN only provide about 23% of the total reionization budget which is dominated by black holes in high stellar mass systems (with M_* ≥10^9M_⊙). This is because AGN number densities become relevant only at z ≤7 - as a result, AGN contribute as much as galaxies as late as z ∼6.2, when reionization is already in its end stages. Finally, we find that even contrasting models of the AGN ionizing photon escape fraction (increasing or decreasing with stellar mass) do not qualitatively change our results.

23. arXiv

    

    Euclid. I. Overview of the Euclid mission

    Euclid Collaboration, Y. Mellier, Abdurro’uf, J. A. Acevedo Barroso, A. Achúcarro, and 195 more authors

    arXiv, May 2024

    Abs DOI

    The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium- class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg\^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high- level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance.

24. arXiv

    

    Euclid. II. The VIS Instrument

    Euclid Collaboration, M. S. Cropper, A. Al-Bahlawan, J. Amiaux, S. Awan, and 195 more authors

    arXiv, May 2024

    Abs DOI

    This paper presents the specification, design, and development of the Visible Camera (VIS) on the ESA Euclid mission. VIS is a large optical-band imager with a field of view of 0.54 deg\^2 sampled at 0.1“ with an array of 609 Megapixels and spatial resolution of 0.18”. It will be used to survey approximately 14,000 deg\^2 of extragalactic sky to measure the distortion of galaxies in the redshift range z=0.1-1.5 resulting from weak gravitational lensing, one of the two principal cosmology probes of Euclid. With photometric redshifts, the distribution of dark matter can be mapped in three dimensions, and, from how this has changed with look-back time, the nature of dark energy and theories of gravity can be constrained. The entire VIS focal plane will be transmitted to provide the largest images of the Universe from space to date, reaching m_AB>24.5 with S/N >10 in a single broad I_E\raisebox-0.5ex~(r+i+z) band over a six year survey. The particularly challenging aspects of the instrument are the control and calibration of observational biases, which lead to stringent performance requirements and calibration regimes. With its combination of spatial resolution, calibration knowledge, depth, and area covering most of the extra-Galactic sky, VIS will also provide a legacy data set for many other fields. This paper discusses the rationale behind the VIS concept and describes the instrument design and development before reporting the pre-launch performance derived from ground calibrations and brief results from the in-orbit commissioning. VIS should reach fainter than m_AB=25 with S/N>10 for galaxies of full-width half-maximum of 0.3“ in a 1.3” diameter aperture over the Wide Survey, and m_AB>26.4 for a Deep Survey that will cover more than 50 deg\^2. The paper also describes how VIS works with the other Euclid components of survey, telescope, and science data processing to extract the cosmological information.

25. arXiv

    

    Euclid. III. The NISP Instrument

    Euclid Collaboration, K. Jahnke, W. Gillard, M. Schirmer, A. Ealet, and 195 more authors

    arXiv, May 2024

    Abs DOI

    The Near-Infrared Spectrometer and Photometer (NISP) on board the Euclid satellite provides multiband photometry and R>=450 slitless grism spectroscopy in the 950-2020nm wavelength range. In this reference article we illuminate the background of NISP’s functional and calibration requirements, describe the instrument’s integral components, and provide all its key properties. We also sketch the processes needed to understand how NISP operates and is calibrated, and its technical potentials and limitations. Links to articles providing more details and technical background are included. NISP’s 16 HAWAII-2RG (H2RG) detectors with a plate scale of 0.3” pix\^-1 deliver a field-of-view of 0.57deg\^2. In photo mode, NISP reaches a limiting magnitude of \raisebox-0.5ex\textasciitilde24.5AB mag in three photometric exposures of about 100s exposure time, for point sources and with a signal-to-noise ratio (SNR) of 5. For spectroscopy, NISP’s point-source sensitivity is a SNR = 3.5 detection of an emission line with flux \raisebox-0.5ex\textasciitilde2x10\^-16erg/s/cm\^2 integrated over two resolution elements of 13.4A, in 3x560s grism exposures at 1.6 mu (redshifted Ha). Our calibration includes on-ground and in-flight characterisation and monitoring of detector baseline, dark current, non-linearity, and sensitivity, to guarantee a relative photometric accuracy of better than 1.5%, and relative spectrophotometry to better than 0.7%. The wavelength calibration must be better than 5A. NISP is the state-of-the-art instrument in the NIR for all science beyond small areas available from HST and JWST - and an enormous advance due to its combination of field size and high throughput of telescope and instrument. During Euclid’s 6-year survey covering 14000 deg\^2 of extragalactic sky, NISP will be the backbone for determining distances of more than a billion galaxies. Its NIR data will become a rich reference imaging and spectroscopy data set for the coming decades.

26. arXiv

    

    Euclid. V. The Flagship galaxy mock catalogue: a comprehensive simulation for the Euclid mission

    Euclid Collaboration, F. J. Castander, P. Fosalba, J. Stadel, D. Potter, and 195 more authors

    arXiv, May 2024

    Abs DOI

    We present the Flagship galaxy mock, a simulated catalogue of billions of galaxies designed to support the scientific exploitation of the Euclid mission. Euclid is a medium-class mission of the European Space Agency optimised to determine the properties of dark matter and dark energy on the largest scales of the Universe. It probes structure formation over more than 10 billion years primarily from the combination of weak gravitational lensing and galaxy clustering data. The breath of Euclid’s data will also foster a wide variety of scientific analyses. The Flagship simulation was developed to provide a realistic approximation to the galaxies that will be observed by Euclid and used in its scientific analyses. We ran a state-of- the-art N-body simulation with four trillion particles, producing a lightcone on the fly. From the dark matter particles, we produced a catalogue of 16 billion haloes in one octant of the sky in the lightcone up to redshift z=3. We then populated these haloes with mock galaxies using a halo occupation distribution and abundance matching approach, calibrating the free parameters of the galaxy mock against observed correlations and other basic galaxy properties. Modelled galaxy properties include luminosity and flux in several bands, redshifts, positions and velocities, spectral energy distributions, shapes and sizes, stellar masses, star formation rates, metallicities, emission line fluxes, and lensing properties. We selected a final sample of 3.4 billion galaxies with a magnitude cut of H_E<26, where we are complete. We have performed a comprehensive set of validation tests to check the similarity to observational data and theoretical models. In particular, our catalogue is able to closely reproduce the main characteristics of the weak lensing and galaxy clustering samples to be used in the mission’s main cosmological analysis. (abridged)

27. arXiv

    

    Euclid: Early Release Observations – Programme overview and pipeline for compact- and diffuse-emission photometry

    J. -C. Cuillandre, E. Bertin, M. Bolzonella, H. Bouy, S. Gwyn, and 195 more authors

    arXiv, May 2024

    Abs DOI

    The Euclid ERO showcase Euclid’s capabilities in advance of its main mission, targeting 17 astronomical objects, from galaxy clusters, nearby galaxies, globular clusters, to star-forming regions. A total of 24 hours observing time was allocated in the early months of operation, engaging the scientific community through an early public data release. We describe the development of the ERO pipeline to create visually compelling images while simultaneously meeting the scientific demands within months of launch, leveraging a pragmatic, data-driven development strategy. The pipeline’s key requirements are to preserve the image quality and to provide flux calibration and photometry for compact and extended sources. The pipeline’s five pillars are: removal of instrumental signatures; astrometric calibration; photometric calibration; image stacking; and the production of science-ready catalogues for both the VIS and NISP instruments. We report a PSF with a full width at half maximum of 0.16“ in the optical and 0.49” in the three NIR bands. Our VIS mean absolute flux calibration is accurate to about 1%, and 10% for NISP due to a limited calibration set; both instruments have considerable colour terms. The median depth is 25.3 and 23.2 AB mag with a SNR of 10 for galaxies, and 27.1 and 24.5 AB mag at an SNR of 5 for point sources for VIS and NISP, respectively. Euclid’s ability to observe diffuse emission is exceptional due to its extended PSF nearly matching a pure diffraction halo, the best ever achieved by a wide-field, high- resolution imaging telescope. Euclid offers unparalleled capabilities for exploring the LSB Universe across all scales, also opening a new observational window in the NIR. Median surface-brightness levels of 29.9 and 28.3 AB mag per square arcsec are achieved for VIS and NISP, respectively, for detecting a 10 arcsec x 10 arcsec extended feature at the 1 sigma level.

28. arXiv

    

    Euclid: Early Release Observations – A preview of the Euclid era through a galaxy cluster magnifying lens

    H. Atek, R. Gavazzi, J. R. Weaver, J. M. Diego, T. Schrabback, and 195 more authors

    arXiv, May 2024

    Abs DOI

    We present the first analysis of the Euclid Early Release Observations (ERO) program that targets fields around two lensing clusters, Abell 2390 and Abell 2764. We use VIS and NISP imaging to produce photometric catalogs for a total of ∼500 000 objects. The imaging data reach a 5\,σtypical depth in the range 25.1-25.4 AB in the NISP bands, and 27.1-27.3 AB in the VIS band. Using the Lyman-break method in combination with photometric redshifts, we identify 30 Lyman-break galaxy (LBG) candidates at z>6 and 139 extremely red sources (ERSs), most likely at lower redshift. The deeper VIS imaging compared to NISP means we can routinely identify high-redshift Lyman breaks of the order of 3 magnitudes, which reduces contamination by brown dwarf stars and low-redshift galaxies. Spectroscopic follow-up campaigns of such bright sources will help constrain both the bright end of the ultraviolet galaxy luminosity function and the quasar luminosity function at z>6, and constrain the physical nature of these objects. Additionally, we have performed a combined strong lensing and weak lensing analysis of A2390, and demonstrate how Euclid will contribute to better constraining the virial mass of galaxy clusters. From these data, we also identify optical and near-infrared counterparts of known z>0.6 clusters, which exhibit strong lensing features, establishing the ability of Euclid to characterize high-redshift clusters. Finally, we provide a glimpse of Euclid’s ability to map the intracluster light out to larger radii than current facilities, enabling a better understanding of the cluster assembly history and mapping of the dark matter distribution. This initial dataset illustrates the diverse spectrum of legacy science that will be enabled by the Euclid survey.

29. arXiv

    Euclid: ERO – NISP-only sources and the search for luminous z=6-8 galaxies

    J. R. Weaver, S. Taamoli, C. J. R. McPartland, L. Zalesky, N. Allen, and 183 more authors

    arXiv, May 2024

    Abs DOI

    This paper presents a search for high redshift galaxies from the Euclid Early Release Observations program “Magnifying Lens.” The 1.5 deg^2 area covered by the twin Abell lensing cluster fields is comparable in size to the few other deep near-infrared surveys such as COSMOS, and so provides an opportunity to significantly increase known samples of rare UV-bright galaxies at z\approx6-8 (M_\rm UV≲-22). Beyond their still uncertain role in reionisation, these UV-bright galaxies are ideal laboratories from which to study galaxy formation and constrain the bright-end of the UV luminosity function. Of the 501994 sources detected from a combined Y_\rm E, J_\rm E, and H_\rm E NISP detection image, 168 do not have any appreciable VIS/I_\rm E flux. These objects span a range in spectral colours, separated into two classes: 139 extremely red sources; and 29 Lyman-break galaxy candidates. Best-fit redshifts and spectral templates suggest the former is composed of both zrsim5 dusty star-forming galaxies and z\approx1-3 quiescent systems. The latter is composed of more homogeneous Lyman break galaxies at z\approx6-8. In both cases, contamination by L- and T-type dwarfs cannot be ruled out with Euclid images alone. Additional contamination from instrumental persistence is investigated using a novel time series analysis. This work lays the foundation for future searches within the Euclid Deep Fields, where thousands more zrsim6 Lyman break systems and extremely red sources will be identified.

30. arXiv

    UNCOVER: Significant Reddening in Cosmic Noon Quiescent Galaxies

    Jared Siegel, David Setton, Jenny Greene, Katherine Suess, Katherine Whitaker, and 17 more authors

    arXiv, Sep 2024

    Abs DOI

    We explore the physical properties of five massive quiescent galaxies at z\sim2.5, revealing the presence of non-negligible dust reservoirs. JWST NIRSpec observations were obtained for each target, finding no significant line emission; multiple star formation tracers independently place upper limits between 0.1-10 M_⊙/ \mathrmyr. Spectral energy distribution modeling with Prospector infers stellar masses between \log_10[M / M_⊙] ∼10-11 and stellar mass-weighted ages between 1-2 Gyr. The inferred mass-weighted effective radii (r_eff∼0.4-1.4 kpc) and inner 1 kpc stellar surface densities (\log_10[Σ/ M_⊙\mathrmkpc^2 ]rsim 9) are typical of quiescent galaxies at z rsim 2. The galaxies display negative color gradients (redder core and bluer outskirts); for one galaxy, this effect results from a dusty core, while for the others it may be evidence of an “inside- out” growth process. Unlike local quiescent galaxies, we identify significant reddening in these typical cosmic noon passive galaxies; all but one require A_V rsim 0.4. This finding is in qualitative agreement with previous studies but our deep 20-band NIRCam imaging is able to significantly suppress the dust-age degeneracy and confidently determine that these galaxies are reddened. We speculate about the physical effects that may drive the decline in dust content in quiescent galaxies over cosmic time.

31. arXiv

    

    UNCOVERing the High-Redshift AGN Population Among Extreme UV Line Emitters

    Helena Treiber, Jenny Greene, John R. Weaver, Tim B. Miller, Lukas J. Furtak, and 21 more authors

    arXiv, Sep 2024

    Abs DOI

    JWST has revealed diverse new populations of high-redshift (z\sim4-11) AGN and extreme star-forming galaxies that challenge current models. In this paper, we use rest-frame UV emission-line diagnostics to identify AGN candidates and other exceptional ionizing sources, complementing previous studies predominantly focused on broad-line AGN. In this paper, we use rest-frame UV emission-line diagnostics to identify AGN candidates and other exceptional ionizing sources, complementing previous studies predominantly focused on broad-line AGN. From a parent sample of 205 \mathrmz_spec>3 UNCOVER galaxies with NIRSpec/PRISM follow-up, we identify 12 C IV, He II, and C III] emitters. Leveraging the combined rest-optical and UV coverage of PRISM, we limit the emission-line model space using the sample’s [O III]/Hβdistribution, significantly decreasing the overlap between AGN and star-formation models in the UV diagnostics. We then find that the five He II emitters are the strongest AGN candidates, with further support from two [Ne V] detections and one X-ray detection from Chandra. We cannot robustly quantify the AGN fraction in this sample, but we note that close to 20% of \mathrmM_*>2\times10^9 M_⊙ parent sample galaxies are AGN candidates. The lower-mass line emitters, which are consistent with both AGN and star-forming photoionization models, have more compact sizes and higher specific star formation rates than the parent sample. Higher-resolution and deeper data on these UV line emitters should provide much stronger constraints on the obscured AGN fraction at z > 3.

32. arXiv

    

    COSMOS-Web: A history of galaxy migrations over the stellar mass-star formation rate plane

    R. C. Arango-Toro, O. Ilbert, L. Ciesla, M. Shuntov, G. Aufort, and 37 more authors

    arXiv, Oct 2024

    Abs DOI

    The stellar mass-star formation rate (\mathrmM_*-\mathrmSFR) plane is a fundamental diagnostic for distinguishing galaxy populations. However, the evolutionary pathways of galaxies within this plane across cosmic time remain poorly understood. This study aims to observationally characterize galaxy migration in the \mathrmM_*-\mathrmSFR plane using reconstructed star formation histories (SFHs) of galaxies at z < 4. Our goal is to provide insights into the physical processes governing star formation and quenching. We analyze a sample of 299,131 galaxies at z < 4 from the COSMOS-Web NIRCam survey (m_\mathrmF444W < 27, 0.54 deg^2). Using non-parametric SFH modeling with CIGALE, we derive physical properties and reconstruct SFHs. To trace galaxy evolution, we define migration vectors, quantifying their direction (\Phi_\mathrmdt [deg]) and velocity norm (r_\mathrmdt [dex/Gyr]) on the \mathrmM_*-\mathrmSFR plane. The reliability of these vectors is assessed using the Horizon-AGN simulation. We find that main-sequence galaxies exhibit low-amplitude migration with scattered directions, suggesting oscillations within the main sequence. Their progenitors predominantly lie on the main sequence 1 Gyr earlier. Starburst galaxies show rapid mass assembly (50% within 350 Myr) and originate from the main sequence, while passive galaxies display uniformly declining SFHs. Massive passive galaxies emerge as early as 3.5 < z < 4, increasing in number density over time. Only <20% of passive galaxies were starbursts 1 Gyr prior, indicating diverse quenching pathways. By reconstructing SFHs to z < 4, we present a coherent picture of galaxy migration in the \mathrmM_*-\mathrmSFR plane, linking evolutionary phases to their star formation signatures.

33. arXiv

    

    Galaxy Size and Mass Build-up in the First 2 Gyrs of Cosmic History from Multi-Wavelength JWST NIRCam Imaging

    Natalie Allen, Pascal A. Oesch, Sune Toft, Jasleen Matharu, Conor J. R. McPartland, and 10 more authors

    arXiv, Oct 2024

    Abs DOI

    The evolution of galaxy sizes in different wavelengths provides unique insights on galaxy build-up across cosmic epochs. Such measurements can now finally be done at z>3 thanks to the exquisite spatial resolution and multi-wavelength capability of the JWST. With the public data from the CEERS, PRIMER-UDS, and PRIMER-COSMOS surveys, we measure the sizes of ∼3500 star- forming galaxies at 3 \leqslant z<9, in 7 NIRCam bands using the multi-wavelength model fitting code GalfitM. The size-mass relation is measured in four redshift bins, across all NIRCam bands. We find that, the slope and intrinsic scatter of the rest-optical size-mass relation are constant across this redshift range and consistent with previous HST-based studies at low-z. When comparing the relations across different wavelengths, the average rest-optical and rest-UV relations are consistent with each other up to z=6, but the intrinsic scatter is largest in rest-UV wavelengths compared to rest- optical and redder bands. This behaviour is independent of redshift and we speculate that it is driven by bursty star- formation in z>4 galaxies. Additionally, for 3\leqslant z<4 star-forming galaxies at \rm M_* > 10^10 M_⊙, we find smaller rest-\rm 1\rm\,μm sizes in comparison to rest- optical (and rest-UV) sizes, suggestive of colour gradients. When comparing to simulations, we find agreement over \rm M_* ≈10^9 - 10^10 M_⊙ but beyond this mass, the observed size-mass relation is significantly steeper. Our results show the power of JWST/NIRCam to provide new constraints on galaxy formation models.

34. arXiv

    

    JWST UNCOVERs the Optical Size - Stellar Mass Relation at 4<z<8: Rapid Growth in the Sizes of Low Mass Galaxies in the First Billion Years of the Universe

    Tim B. Miller, Katherine A. Suess, David J. Setton, Sedona H. Price, Ivo Labbe, and 19 more authors

    arXiv, Dec 2024

    Abs DOI

    We study the rest-frame optical and ultraviolet morphology of galaxies in the first billion years of the Universe. Using JWST data from the UNCOVER and MegaScience surveys targeting the lensing cluster Abell 2744 we present multi-band morphological measurements for a sample of 995 galaxies selected using 20-band NIRCam photometry and 35 using NIRSpec Prism spectroscopy over the redshift range of 4<z<8. The wavelength-dependent morphology is measured using pysersic by simultaneously modeling the images in 6 NIRCam wide filters covering the rest-frame UV to optical. The joint modeling technique increases the precision of measured radii by 50\%. Galaxies in our sample show a wide range of Sersic indices, with no systematic difference between optical and UV morphology. We model the size- mass relation in a Bayesian manner using a continuity model to directly fit the redshift evolution while accounting for observational uncertainties. We find the average size of galaxies at \log M_*/M_⊙=8.5 grows rapidly, from 400 pc at z=8 to 830 pc at z=4. This is faster evolution than expected from power law scalings of the Hubble parameter or scale factor that describe well previous results at z<2. This suggests that different and/or much stronger processes affect low mass systems during the epoch of reionization. The measured logarithmic slope (0.25) and scatter (0.23 dex) are non-evolving. We discuss the remarkable consistency of the slope and scatter over cosmic time in the context of the galaxy-halo connection.

35. MNRAS

    

    JWST UNCOVER: the overabundance of ultraviolet-luminous galaxies at z > 9

    Iryna Chemerynska, Hakim Atek, Lukas J. Furtak, Adi Zitrin, Jenny E. Greene, and 18 more authors

    Monthly Notices of the Royal Astronomical Society, Jun 2024

    Abs DOI

    Over the past year, JWST has uncovered galaxies at record-breaking distances up to z \raisebox-0.5ex~13. The JWST UNCOVER (ultra-deep NIRSpec and NIRcam observations before the epoch of reionization) program has obtained ultra-deep multiwavelength NIRCam imaging of the massive galaxy cluster A2744 over \raisebox-0.5ex\textasciitilde45 arcmin^2 down to \raisebox-0.5ex\textasciitilde29.5 AB mag. Here, we present a robust ultraviolet (UV) luminosity function derived through lensing clusters at 9 < z < 12. Using comprehensive end-to-end simulations, we account for all lensing effects and systematic uncertainties in deriving both the amplification factors and the effective survey volume. Our results confirm the intriguing excess of UV-bright galaxies (M_UV <-20 AB mag) previously reported at z > 9 in recent JWST studies. In particular, a double power-law (DPL) describes better the bright end of the luminosity function compared to the classical Schechter form. The number density of these bright galaxies is 10-100 times larger than theoretical predictions and previous findings based on Hubble Space Telescope (HST) observations. Additionally, we measure a star formation rate density of \ensuremathρ_SFR = 10^-2.64 M_\ensuremath⊙ yr^-1 Mpc^-3 at these redshifts, which is 4-10 times higher than galaxy formation models that assume a constant star formation efficiency. Future wide-area surveys and accurate modelling of lensing-assisted observations will reliably constrain both the bright and the dim end of the UV luminosity function at z > 9, which will provide key benchmarks for galaxy formation models.

36. MNRAS

    

    Galaxy build-up in the first 1.5 Gyr of cosmic history: insights from the stellar mass function at z 4-9 from JWST NIRCam observations

    Andrea Weibel, Pascal A. Oesch, Laia Barrufet, Rashmi Gottumukkala, Richard S. Ellis, and 26 more authors

    Monthly Notices of the Royal Astronomical Society, Sep 2024

    Abs DOI

    Combining the public JWST/NIRCam imaging programs CEERS, PRIMER, and JADES, spanning a total area of ∼500 \rm arcmin^2, we obtain a sample of 30 000 galaxies at z_\rm phot∼4\!-\!9 that allows us to perform a complete, rest-optical- selected census of the galaxy population at z 3. Comparing the stellar mass M_* and the UV-slope βdistributions between JWST- and HST-selected samples, we generally find very good agreement and no significant biases. Nevertheless, JWST enables us to probe a new population of UV-red galaxies that was missing from previous HST-based Lyman-break galaxy (LBG) samples. We measure galaxy stellar mass functions (SMFs) at z∼4\!-\!9 down to limiting masses of 10^7.5\!-\!10^8.5 \rm M_⊙, finding steep low-mass slopes over the entire redshift range, reaching values of α≈-2 at zrsim 6. At the high-mass end, UV-red galaxies dominate at least out to z∼6. The implied redshift evolution of the SMF suggests a rapid build-up of massive dust-obscured or quiescent galaxies from z∼6 to z∼4 as well as an enhanced efficiency of star formation towards earlier times (zrsim 6). Finally, we show that the galaxy mass density grows by a factor ∼20\times from z∼9 to z∼4. Our results emphasize the importance of rest-frame optically selected samples in inferring accurate distributions of physical properties and studying the mass build-up of galaxies in the first 1.5 Gyr of cosmic history.

37. Nature

    Most of the photons that reionized the Universe came from dwarf galaxies

    Hakim Atek, Ivo Labbé, Lukas J. Furtak, Iryna Chemerynska, Seiji Fujimoto, and 28 more authors

    Nature, Feb 2024

    Abs DOI

    The identification of sources driving cosmic reionization, a major phase transition from neutral hydrogen to ionized plasma around 600-800 Myr after the Big Bang^1-3, has been a matter of debate^4. Some models suggest that high ionizing emissivity and escape fractions (f_esc) from quasars support their role in driving cosmic reionization^5,6. Others propose that the high f_esc values from bright galaxies generate sufficient ionizing radiation to drive this process^7. Finally, a few studies suggest that the number density of faint galaxies, when combined with a stellar-mass-dependent model of ionizing efficiency and f_esc, can effectively dominate cosmic reionization^8,9. However, so far, comprehensive spectroscopic studies of low-mass galaxies have not been done because of their extreme faintness. Here we report an analysis of eight ultra-faint galaxies (in a very small field) during the epoch of reionization with absolute magnitudes between M_UV \ensuremath≈ \ensuremath-17 mag and \ensuremath-15 mag (down to 0.005L^\ensuremath⋆ (refs. ^10,11)). We find that faint galaxies during the first thousand million years of the Universe produce ionizing photons with log[\ensuremathξ_ion (Hz erg^\ensuremath-1)] = 25.80 \ensuremath\pm 0.14, a factor of 4 higher than commonly assumed values^12. If this field is representative of the large-scale distribution of faint galaxies, the rate of ionizing photons exceeds that needed for reionization, even for escape fractions of the order of 5%.

38. Nature

    A high black-hole-to-host mass ratio in a lensed AGN in the early Universe

    Lukas J. Furtak, Ivo Labbé, Adi Zitrin, Jenny E. Greene, Pratika Dayal, and 33 more authors

    Nature, Apr 2024

    Abs DOI

    Early JWST observations have uncovered a population of red sources that might represent a previously overlooked phase of supermassive black hole growth^1-3. One of the most intriguing examples is an extremely red, point-like object that was found to be triply imaged by the strong lensing cluster Abell 2744 (ref. ^4). Here we present deep JWST/NIRSpec observations of this object, Abell2744-QSO1. The spectroscopy confirms that the three images are of the same object, and that it is a highly reddened (A_V ≃ 3) broad emission line active galactic nucleus at a redshift of z_spec = 7.0451 \ensuremath\pm 0.0005. From the width of H\ensuremathβ (full width at half-maximum = 2,800 \ensuremath\pm 250 km s^\ensuremath-1), we derive a black hole mass of M_BH=4_\ensuremath-1^+2\texttimes1 0^7M_\ensuremath⊙ . We infer a very high ratio of black-hole-to-galaxy mass of at least 3%, an order of magnitude more than that seen in local galaxies^5 and possibly as high as 100%. The lack of strong metal lines in the spectrum together with the high bolometric luminosity (L_bol = (1.1 \ensuremath\pm 0.3) \texttimes 10^45 erg s^\ensuremath-1) indicate that we are seeing the black hole in a phase of rapid growth, accreting at 30% of the Eddington limit. The rapid growth and high black-hole-to-galaxy mass ratio of Abell2744-QSO1 suggest that it may represent the missing link between black hole seeds^6 and one of the first luminous quasars^7.

</ol>

2023

1. A&A

   

   Combining the CLAUDS and HSC-SSP surveys. U + grizy(+YJHK_s) photometry and photometric redshifts for 18M galaxies in the 20 deg^2 of the HSC-SSP Deep and ultraDeep fields

   G. Desprez, V. Picouet, T. Moutard, S. Arnouts, M. Sawicki, and 19 more authors

   Astronomy & Astrophysics, Feb 2023

   Abs DOI

   We present the combination of the Canada-France-Hawaii Telescope (CHFT) Large Area U-bands Deep Survey (CLAUDS) and the Hyper-Suprime- Cam (HSC) Subaru Strategic Program (HSC-SSP) data over their four deep fields. We provide photometric catalogs for u, u^* (CFHT-MegaCam), g, r, i, z, and y (Subaru-HSC) bands over \raisebox-0.5ex\textasciitilde20 deg^2, complemented in two fields by data from the Visible and Infrared Survey Telescope for Astronomy (VISTA) Deep Extragalactic Observations (VIDEO) survey and the UltraVISTA survey, thus extending the wavelength coverage toward near-infrared with VIRCAM Y, J, H, and K_s observations over 5.5 deg^2. The extraction of the photometry was performed with two different softwares: the HSC pipeline hscPipe and the standard and robust SExtractor software. Photometric redshifts were computed with template- fitting methods using the new Phosphoros code for the hscPipe photometry and the well-known Le Phare code for the SExtractor photometry. The products of these methods were compared with each other in detail. We assessed their quality using the large spectroscopic sample available in those regions, together with photometry and photometric redshifts from COSMOS2020, the latest version of the Cosmic Evolution Survey catalogs. We find that both photometric data sets are in good agreement in Ugrizy down to magnitude \raisebox-0.5ex\textasciitilde26, and to magnitude \raisebox-0.5ex\textasciitilde24.5 in the YJHK_s bands. We achieve good performance for the photometric redshifts, reaching precisions of \ensuremathσ_NMAD \ensuremath≲ 0.04 down to m_i \raisebox-0.5ex~25, even using only the CLAUDS and HSC bands. At the same magnitude limit, we measured an outlier fraction of \ensuremathη \ensuremath≲ 10% when using the Ugrizy bands, and down to \ensuremathη \ensuremath≲ 6% when considering near-infrared data. The hscPipe plus Phosphoros pipeline performs slightly worse in terms of photometric-redshifts precision and outlier fraction than its SExtractor plus Le Phare counterpart, which has essentially been tracked down to differences in the photometry. Thus, this work is also a validation of the Phosphoros code. The photometric catalogs with the data and photometric redshifts from the two pipelines are presented and made publicly available. \\textbackslashThe catalogs are also available at the CDS via anonymous ftp to <A href=“https://cdsarc.cds.unistra.fr”>cdsarc.cds.unistra.fr</A> (ftp://130.79.128.5) or via <A href=“https://cdsarc.cds.unistra.fr/viz- bin/cat/J/A+A/670/A82”>https://cdsarc.cds.unistra.fr/viz- bin/cat/J/A+A/670/A82</A>

2. A&A

   

   Massive galaxy formation caught in action at z ∼ 5 with JWST

   Shuowen Jin, Nikolaj B. Sillassen, Georgios E. Magdis, Aswin P. Vijayan, Gabriel B. Brammer, and 11 more authors

   Astronomy & Astrophysics, Feb 2023

   Abs DOI

   We report the discovery of a compact group of galaxies, CGG-z5, at z \ensuremath∼ 5.2 in the EGS field covered by the JWST/CEERS survey. CGG-z5 was selected as the highest overdensity of galaxies at z > 2 in recent JWST public surveys and it consists of six candidate members lying within a projected area of 1.5″ \texttimes 3″ (10\texttimes20 kpc^2). All group members are HST/F435W and HST/F606W dropouts while securely detected in the JWST/NIRCam bands, yielding a narrow range of robust photometric redshifts 5.0 < z < 5.3. The most massive galaxy in the group has a stellar mass l og(M_*/M_\ensuremath⊙)\ensuremath≈9.8, while the rest are low-mass satellites (log(M_*/M_\ensure math⊙)\ensuremath≈8.4-9.2). While several group members were already detected in the HST and IRAC bands, the low stellar masses and the compactness of the structure required the sensitivity and resolution of JWST for its identification. To assess the nature and evolutionary path of CGG-z5, we searched for similar compact structures in the EAGLE simulations and followed their evolution with time. We find that all the identified structures merge into a single galaxy by z = 3 and form a massive galaxy (log(M_*/M_\ensuremath⊙)> 11) at z \ensuremath∼ 1. This implies that CGG-z5 could be a “proto-massive galaxy” captured during a short-lived phase of massive galaxy formation.

3. A&A

   

   Euclid preparation. XXV. The Euclid Morphology Challenge: Towards model-fitting photometry for billions of galaxies

   Euclid Collaboration, E. Merlin, M. Castellano, H. Bretonnière, M. Huertas-Company, and 195 more authors

   Astronomy & Astrophysics, Mar 2023

   Abs DOI

   The European Space Agency’s Euclid mission will provide high-quality imaging for about 1.5 billion galaxies. A software pipeline to automatically process and analyse such a huge amount of data in real time is being developed by the Science Ground Segment of the Euclid Consortium; this pipeline will include a model- fitting algorithm, which will provide photometric and morphological estimates of paramount importance for the core science goals of the mission and for legacy science. The Euclid Morphology Challenge is a comparative investigation of the performance of five model-fitting software packages on simulated Euclid data, aimed at providing the baseline to identify the best-suited algorithm to be implemented in the pipeline. In this paper we describe the simulated dataset, and we discuss the photometry results. A companion paper is focussed on the structural and morphological estimates. We created mock Euclid images simulating five fields of view of 0.48 deg^2 each in the I_E band of the VIS instrument, containing a total of about one and a half million galaxies (of which 350 000 have a nominal signal-to-noise ratio above 5), each with three realisations of galaxy profiles (single and double Sérsic, and ’realistic’ profiles obtained with a neural network); for one of the fields in the double Sérsic realisation, we also simulated images for the three near-infrared Y_E, J_E, and H_E bands of the NISP-P instrument, and five Rubin/LSST optical complementary bands (u, g, r, i, and z), which together form a typical dataset for an Euclid observation. The images were simulated at the expected Euclid Wide Survey depths. To analyse the results, we created diagnostic plots and defined metrics to take into account the completeness of the provided catalogues, as well as the median biases, dispersions, and outlier fractions of their measured flux distributions. Five model-fitting software packages (DeepLeGATo, Galapagos-2, Morfometryka, ProFit, and SourceXtractor++) were compared, all typically providing good results. Of the differences among them, some were at least partly due to the distinct strategies adopted to perform the measurements. In the best-case scenario, the median bias of the measured fluxes in the analytical profile realisations is below 1% at a signal-to-noise ratio above 5 in I_E, and above 10 in all the other bands; the dispersion of the distribution is typically comparable to the theoretically expected one, with a small fraction of catastrophic outliers. However, we can expect that real observations will prove to be more demanding, since the results were found to be less accurate for the most realistic realisation. We conclude that existing model-fitting software can provide accurate photometric measurements on Euclid datasets. The results of the challenge are fully available and reproducible through an online plotting tool.

4. A&A

   

   Euclid preparation. XXVI. The Euclid Morphology Challenge: Towards structural parameters for billions of galaxies

   Euclid Collaboration, H. Bretonnière, U. Kuchner, M. Huertas-Company, E. Merlin, and 195 more authors

   Astronomy & Astrophysics, Mar 2023

   Abs DOI

   The various Euclid imaging surveys will become a reference for studies of galaxy morphology by delivering imaging over an unprecedented area of 15 000 square degrees with high spatial resolution. In order to understand the capabilities of measuring morphologies from Euclid-detected galaxies and to help implement measurements in the pipeline of the Organisational Unit MER of the Euclid Science Ground Segment, we have conducted the Euclid Morphology Challenge, which we present in two papers. While the companion paper focusses on the analysis of photometry, this paper assesses the accuracy of the parametric galaxy morphology measurements in imaging predicted from within the Euclid Wide Survey. We evaluate the performance of five state-of-the-art surface-brightness-fitting codes, DeepLeGATo, Galapagos-2, Morfometryka, ProFit and SourceXtractor++, on a sample of about 1.5 million simulated galaxies (350 000 above 5\ensuremathσ) resembling reduced observations with the Euclid VIS and NIR instruments. The simulations include analytic Sérsic profiles with one and two components, as well as more realistic galaxies generated with neural networks. We find that, despite some code-specific differences, all methods tend to achieve reliable structural measurements (< 10% scatter on ideal Sérsic simulations) down to an apparent magnitude of about I_E = 23 in one component and I_E = 21 in two components, which correspond to a signal-to-noise ratio of approximately 1 and 5, respectively. We also show that when tested on non-analytic profiles, the results are typically degraded by a factor of 3, driven by systematics. We conclude that the official Euclid Data Releases will deliver robust structural parameters for at least 400 million galaxies in the Euclid Wide Survey by the end of the mission. We find that a key factor for explaining the different behaviour of the codes at the faint end is the set of adopted priors for the various structural parameters.

5. A&A

   

   HSC-CLAUDS survey: The star formation rate functions since z ∼ 2 and comparison with hydrodynamical simulations

   V. Picouet, S. Arnouts, E. Le Floc’h, T. Moutard, K. Kraljic, and 14 more authors

   Astronomy & Astrophysics, Jul 2023

   Abs DOI

   Context. Star formation rate functions (SFRFs) give an instantaneous view of the distribution of star formation rates (SFRs) in galaxies at different epochs. They are a complementary and more stringent test for models than the galaxy stellar mass function, which gives an integrated view of the past star formation activity. However, the exploration of SFRFs has been limited thus far due to difficulties in assessing the SFR from observed quantities and probing the SFRF over a wide range of SFRs. \Aims: We overcome these limitations thanks to an original method that predicts the infrared luminosity from the rest-frame UV/optical color of a galaxy and then its SFR over a wide range of stellar masses and redshifts. We applied this technique to the deep imaging survey HSC-CLAUDS combined with near-infrared and UV photometry. We provide the first SFR functions with reliable measurements in the high- and low-SFR regimes up to z = 2 and compare our results with previous observations and four state-of-the-art hydrodynamical simulations. \Methods: The SFR estimates are based on the calibration of the infrared excess (IRX = L_IR/L_UV) in the NUVrK color-color diagram. We improved upon the original calibration in the COSMOS field by incorporating Herschel photometry, which allowed us to extend the analysis to higher redshifts and to galaxies with lower stellar masses using stacking techniques. Our NrK method leads to an accuracy of individual SFR estimates of \ensuremathσ \ensuremath∼ 0.25 dex. We show that it reproduces the evolution of the main sequence up to z = 2 and the behavior of the attenuation (or ⟨IRX⟩) with stellar mass. In addition to the known lack of evolution of this relation up to z = 2 for galaxies with M_\ensuremath⋆ \ensuremath≤ 10^10.3 M_\ensuremath⊙, we observe a plateau in ⟨IRX⟩ at higher stellar masses that depends on redshift. \Results: We measure the SFR functions and cosmic SFR density up to z = 2 for a mass-selected star-forming galaxy sample (with a mass limit of M_\ensuremath⋆ \ensuremath≥ 2.10^9 M_\ensuremath⊙ at z = 2). The SFR functions cover a wide range of SFRs (0.01 \ensuremath≤ SFR \ensuremath≤ 1000 M_\ensuremath⊙ yr^\ensuremath-1), providing good constraints on their shapes. They are well fitted by a Schechter function after accounting for the Eddington bias. The high-SFR tails match the far-infrared observations well, and show a strong redshift evolution of the Schechter parameter, SFR^\ensuremath⋆, as log_10(SFR\ensuremath⋆) = 5.8z + 0.76. The slope of the SFR functions, \ensuremathα, shows almost no evolution up to z = 1.5 \ensuremath- 2 with \ensuremathα = \ensuremath-1.3 \ensuremath\pm 0.1. We compare the SFR functions with predictions from four state-of-the-art hydrodynamical simulations. Significant differences are observed between them, and none of the simulations are able to reproduce the observed SFRFs over the whole redshift and SFR range. We find that only one simulation is able to predict the fraction of highly star-forming galaxies at high z, 1 \ensuremath≤ z \ensuremath≤ 2. This highlights the benefits of using SFRFs as a constraint that can be reproduced by simulations; however, despite efforts to incorporate more physically motivated prescriptions for star- formation and feedback processes, its use remains challenging.

6. A&A

   

   Dust giant: Extended and clumpy star-formation in a massive dusty galaxy at z = 1.38

   Vasily Kokorev, Shuowen Jin, Carlos Gómez-Guijarro, Georgios E. Magdis, Francesco Valentino, and 6 more authors

   Astronomy & Astrophysics, Sep 2023

   Abs DOI

   We present NOEMA CO (2-1) line and ALMA 870 \textmum continuum observations of a main-sequence galaxy at z = 1.38. The galaxy was initially deemed a “gas giant” based on the gas mass derived from sub-mm continuum (log(M_gas/M_\ensuremath⊙) = 11.20 \ensuremath\pm 0.20), however, the gas mass derived from CO (2\ensuremath-1) luminosity brings the gas mass value down to a level that is consistent with typical values for star- forming galaxies at that redshift (log(M_gas/M_\ensuremath⊙) = 10.84 \ensuremath\pm 0.03). Meanwhile, the dust-to-stellar mass ratio remains elevated above the scaling relations by a factor of 5. In this work, we explore the potential physical picture and consider an underestimated stellar mass and optically thick dust as possible explanations. Based on the updated gas-to- stellar mass ratio, we can rule out the former; while the latter may indeed contribute to the overestimation of the dust mass, it is not sufficient enough to explain the observed physical picture overall. Instead, other plausible explanations include enhanced HI reservoirs, an unusually high metallicity, or the presence of an optically dark, dusty contaminant. Using the ALMA data at 870 \textmum coupled with HST/ACS imaging, we find an extended morphology in dust continuum and clumpy star-formation in rest-frame UV in this galaxy. In addition, a tentative \raisebox-0.5ex\textasciitilde10 kpc dusty arm is found to be bridging the galaxy center and a clump in F814W image. The galaxy shows levels of dust obscuration similar to the so-called HST-dark galaxies at higher redshifts, thus falling into the optically faint and dark JWST color-color selection at z > 2. It is therefore possible that our object may stand as a low-z analog of the HST-dark populations. This galaxy serves as a caveat to the gas masses based on the continuum alone, with a larger sample required to unveil the full picture.

7. A&A

   

   COSMOS2020: The galaxy stellar mass function. The assembly and star formation cessation of galaxies at 0.2< z ≤ 7.5

   J. R. Weaver, I. Davidzon, S. Toft, O. Ilbert, H. J. McCracken, and 28 more authors

   Astronomy & Astrophysics, Sep 2023

   Abs DOI

   Context. How galaxies form, assemble, and cease their star formation is a central question within the modern landscape of galaxy evolution studies. These processes are indelibly imprinted on the galaxy stellar mass function (SMF), and its measurement and understanding is key to uncovering a unified theory of galaxy evolution. \Aims: We present constraints on the shape and evolution of the galaxy SMF, the quiescent galaxy fraction, and the cosmic stellar mass density across 90% of the history of the Universe from z = 7.5 \textrightarrow 0.2 as a means to study the physical processes that underpin galaxy evolution. \Methods: The COSMOS survey is an ideal laboratory for studying representative galaxy samples. Now equipped with deeper and more homogeneous near-infrared coverage exploited by the COSMOS2020 catalog, we leverage the large 1.27 deg^2 effective area to improve sample statistics and understand spatial variations (cosmic variance) - particularly for rare, massive galaxies - and push to higher redshifts with greater confidence and mass completeness than previous studies. We divide the total stellar mass function into star-forming and quiescent subsamples through NUVrJ color-color selection. The measurements are then fit with single- and double-component Schechter functions to infer the intrinsic galaxy stellar mass function, the evolution of its key parameters, and the cosmic stellar mass density out to z = 7.5. Finally, we compare our measurements to predictions from state-of-the-art cosmological simulations and theoretical dark matter halo mass functions. \Results: We find a smooth, monotonic evolution in the galaxy stellar mass function since z = 7.5, in general agreement with previous studies. The number density of star- forming systems have undergone remarkably consistent growth spanning four decades in stellar mass from z = 7.5 \textrightarrow 2 whereupon high-mass systems become predominantly quiescent (“downsizing”). Meanwhile, the assembly and growth of low-mass quiescent systems only occurred recently, and rapidly. An excess of massive systems at z \ensuremath≈ 2.5 \ensuremath- 5.5 with strikingly red colors, with some being newly identified, increase the observed number densities to the point where the SMF cannot be reconciled with a Schechter function. \Conclusions: Systematics including cosmic variance and/or active galactic nuclei contamination are unlikely to fully explain this excess, and so we speculate that they may be dust-obscured populations similar to those found in far infrared surveys. Furthermore, we find a sustained agreement from z \ensuremath≈ 3 \ensuremath- 6 between the stellar and dark matter halo mass functions for the most massive systems, suggesting that star formation in massive halos may be more efficient at early times. \\textbackslashData files containing sample IDs and key measurements are available for download: <A href=“https://doi.org/10.5281/zenodo.7808832” >https://doi.org/10.5281/zenodo.7808832</A>

8. AJ

   

   COSMOS2020: Exploring the Dawn of Quenching for Massive Galaxies at 3 < z < 5 with a New Color-selection Method

   Katriona M. L. Gould, Gabriel Brammer, Francesco Valentino, Katherine E. Whitaker, John. R. Weaver, and 13 more authors

   The Astronomical Journal, Jun 2023

   Abs DOI

   We select and characterize a sample of massive (log(M _*/M _\ensuremath⊙) > 10.6) quiescent galaxies (QGs) at 3 < z < 5 in the latest Cosmological Evolution Survey catalog (COSMOS2020). QGs are selected using a new rest-frame color- selection method, based on their probability of belonging to the quiescent group defined by a Gaussian mixture model (GMM) trained on rest-frame colors (NUV - U, U - V, V - J) of similarly massive galaxies at 2 < z < 3. We calculate the quiescent probability threshold above which a galaxy is classified as quiescent using simulated galaxies from the SHARK semi-analytical model. We find that, at z \ensuremath≥ 3 in SHARK, the GMM/NUVU - VJ method outperforms classical rest- frame UVJ selection and is a viable alternative. We select galaxies as quiescent based on their probability in COSMOS2020 at 3 < z < 5, and compare the selected sample to both UVJ- and NUVrJ-selected samples. We find that, although the new selection matches UVJ and NUVrJ in number, the overlap between color selections is only \raisebox-0.5ex\textasciitilde50%-80%, implying that rest-frame color commonly used at lower-redshift selections cannot be equivalently used at z > 3. We compute median rest-frame spectral energy distributions for our sample and find the median QG at 3 < z < 5 has a strong Balmer/4000 Å break, and residual NUV flux indicating recent quenching. We find the number densities of the entire quiescent population (including post-starbursts) more than doubles from 3.5 \ensuremath\pm 2.2 \texttimes 10^-6 Mpc^-3 at 4 < z < 5 to 1.4 \ensuremath\pm 0.4 \texttimes 10^-5 Mpc^-3 at 3 < z < 4, confirming that the onset of massive galaxy quenching occurs as early as 3 < z < 5.

9. ApJ

   

   A Machine-learning Approach to Predict Missing Flux Densities in Multiband Galaxy Surveys

   Nima Chartab, Bahram Mobasher, Asantha R. Cooray, Shoubaneh Hemmati, Zahra Sattari, and 19 more authors

   The Astrophysical Journal, Jan 2023

   Abs DOI

   We present a new method based on information theory to find the optimal number of bands required to measure the physical properties of galaxies with desired accuracy. As a proof of concept, using the recently updated COSMOS catalog (COSMOS2020), we identify the most relevant wave bands for measuring the physical properties of galaxies in a Hawaii Two-0- (H20) and UVISTA-like survey for a sample of i < 25 AB mag galaxies. We find that with the available i-band fluxes, r, u, IRAC/ch2, and z bands provide most of the information regarding the redshift with importance decreasing from r band to z band. We also find that for the same sample, IRAC/ch2, Y, r, and u bands are the most relevant bands in stellar-mass measurements with decreasing order of importance. Investigating the intercorrelation between the bands, we train a model to predict UVISTA observations in near- IR from H20-like observations. We find that magnitudes in the YJH bands can be simulated/predicted with an accuracy of 1\ensuremathσ mag scatter \ensuremath≲0.2 for galaxies brighter than 24 AB mag in near-IR bands. One should note that these conclusions depend on the selection criteria of the sample. For any new sample of galaxies with a different selection, these results should be remeasured. Our results suggest that in the presence of a limited number of bands, a machine-learning model trained over the population of observed galaxies with extensive spectral coverage outperforms template fitting. Such a machine-learning model maximally comprises the information acquired over available extensive surveys and breaks degeneracies in the parameter space of template fitting inevitable in the presence of a few bands.

10. ApJ

    

    Cosmic Evolution of Gas and Star Formation

    Nick Scoville, Andreas Faisst, John Weaver, Sune Toft, Henry J. McCracken, and 18 more authors

    The Astrophysical Journal, Feb 2023

    Abs DOI

    Atacama Large Millimeter/submillimeter Array (ALMA) observations of the long-wavelength dust continuum are used to estimate the gas masses in a sample of 708 star-forming galaxies at z = 0.3-4.5. We determine the dependence of gas masses and star formation efficiencies (SFEs; SFR per unit gas mass) on redshift (z), M _*, and star formation rate (SFR) relative to the main sequence (MS). We find that 70% of the increase in SFRs of the MS is due to the increased gas masses at earlier epochs, while 30% is due to increased efficiency of star formation (SF). For galaxies above the MS this is reversed-with 70% of the increased SFR relative to the MS being due to elevated SFEs. Thus, the major evolution of star formation activity at early epochs is driven by increased gas masses, while the starburst activity taking galaxies above the MS is due to enhanced triggering of star formation (likely due to galactic merging). The interstellar gas peaks at z = 2 and dominates the stellar mass down to z = 1.2. Accretion rates needed to maintain continuity of the MS evolution reach >100 M _\ensuremath⊙ yr^-1 at z > 2. The galactic gas contents are likely the driving determinant for both the rise in SF and AGN activity from z = 5 to their peak at z = 2 and subsequent fall at lower z. We suggest that for self-gravitating clouds with supersonic turbulence, cloud collisions and the filamentary structure of the clouds regulate the star formation activity. ^* 2022 AAS Russell Lecture by Scoville. We provide the science background behind the Russell Lecture and draw extensively on previous work in Scoville et al. ().

11. ApJ

    

    COSMOS2020: Identification of High-z Protocluster Candidates in COSMOS

    Malte Brinch, Thomas R. Greve, John R. Weaver, Gabriel Brammer, Olivier Ilbert, and 19 more authors

    The Astrophysical Journal, Feb 2023

    Abs DOI

    We conduct a systematic search for protocluster candidates at z \ensuremath≥ 6 in the Cosmic Evolution Survey (COSMOS) field using the recently released COSMOS2020 source catalog. We select galaxies using a number of selection criteria to obtain a sample of galaxies that have a high probability of being inside a given redshift bin. We then apply overdensity analysis to the bins using two density estimators, a Weighted Adaptive Kernel estimator and a Weighted Voronoi Tessellation estimator. We have found 15 significant (>4\ensuremathσ) candidate galaxy overdensities across the redshift range 6 \ensuremath≤ z \ensuremath≤ 7.7. The majority of the galaxies appear to be on the galaxy main sequence at their respective epochs. We use multiple stellar-mass-to-halo-mass conversion methods to obtain a range of dark matter halo mass estimates for the overdensities in the range of \raisebox-0.5ex~10^11-10^13 M _\ensuremath⊙, at the respective redshifts of the overdensities. The number and the masses of the halos associated with our protocluster candidates are consistent with what is expected from the area of a COSMOS-like survey in a standard \ensuremathΛ cold dark matter cosmology. Through comparison with simulation, we expect that all of the overdensities at z ≃ 6 will evolve into Virgo-/Coma-like clusters at present (i.e., with masses \raisebox-0.5ex~10^14-10^15 M _\ensuremath⊙). Compared to other overdensities identified at z \ensuremath≥ 6 via narrowband selection techniques, the overdensities presented appear to have \raisebox-0.5ex\textasciitilde10\texttimes higher stellar masses and star formation rates (SFRs). We compare the evolution in the total SFR and stellar mass content of the protocluster candidates across the redshift range 6 \ensuremath≤ z \ensuremath≤ 7.7 and find agreement with the total average SFR from simulations.

12. ApJL

    

    Inferring More from Less: Prospector as a Photometric Redshift Engine in the Era of JWST

    Bingjie Wang, Joel Leja, Rachel Bezanson, Benjamin D. Johnson, Gourav Khullar, and 4 more authors

    The Astrophysical Journal Letters, Feb 2023

    Abs DOI

    The advent of the James Webb Space Telescope (JWST) signals a new era in exploring galaxies in the high-z universe. Current and upcoming JWST imaging will potentially detect galaxies at z \raisebox-0.5ex~20, creating a new urgency in the quest to infer accurate photometric redshifts (photo-z) for individual galaxies from their spectral energy distributions, as well as masses, ages, and star formation rates. Here we illustrate the utility of informed priors encoding previous observations of galaxies across cosmic time in achieving these goals. We construct three joint priors encoding empirical constraints of redshifts, masses, and star formation histories in the galaxy population within the Prospector Bayesian inference framework. In contrast with uniform priors, our model breaks an age-mass-redshift degeneracy, and thus reduces the mean bias error in masses from 0.3 to 0.1 dex, and in ages from 0.6 to 0.2 dex in tests done on mock JWST observations. Notably, our model recovers redshifts at least as accurately as the state-of-the-art photo-z code EAzY in deep JWST fields, but with two advantages: tailoring a model based on a particular survey is rendered mostly unnecessary given well-motivated priors; obtaining joint posteriors describing stellar, active galactic nuclei, gas, and dust contributions becomes possible. We can now confidently use the joint distribution to propagate full non- Gaussian redshift uncertainties into inferred properties of the galaxy population. This model, “Prospector-\ensuremathβ,” is intended for fitting galaxy photometry where the redshift is unknown, and will be instrumental in ensuring the maximum science return from forthcoming photometric surveys with JWST. The code is made publicly available online as a part of Prospector ^9 ^9 The version used in this work corresponds to the state of the Git repository at commit https://github.com/bd-j/prospector/comm it/820ad72363a1f9c22cf03610bfe6e361213385cd..

13. ApJL

    

    COSMOS2020: Discovery of a Protocluster of Massive Quiescent Galaxies at z = 2.77

    Kei Ito, Masayuki Tanaka, Francesco Valentino, Sune Toft, Gabriel Brammer, and 7 more authors

    The Astrophysical Journal Letters, Mar 2023

    Abs DOI

    Protoclusters of galaxies have been found in the last quarter-century. However, most of them have been found through the overdensity of star-forming galaxies, and there have been no known structures identified by more than two spectroscopically confirmed quiescent galaxies at z > 2.5. In this letter, we report the discovery of an overdense structure of massive quiescent galaxies with the spectroscopic redshift z = 2.77 in the COSMOS field, QO-1000. We first photometrically identify this structure as a 4.2\ensuremathσ overdensity with 14 quiescent galaxies in 7 \texttimes 4 pMpc^2 from the COSMOS2020 catalog. We then securely confirm the spectroscopic redshifts of four quiescent galaxies by detecting multiple Balmer absorption lines with Keck/MOSFIRE. All the spectroscopically confirmed members are massive ( \mathrmlog(M_⋆/M_⊙) 11.0 ) and located in a narrow redshift range (2.76 < z < 2.79). Moreover, three of them are in the 1 \texttimes 1 pMpc^2 in the transverse direction at the same redshift (z = 2.760-2.763). Such a concentration of four spectroscopically confirmed quiescent galaxies implies that QO-1000 is >68 times denser than the general field. In addition, we confirm that they form a red sequence in the J - K _ s color. This structure’s halo mass is estimated as \mathrmlog(M_\mathrmhalo/M_⊙) 13.2 from its stellar mass. Similar structures found in the IllustrisTNG simulation are expected to evolve into massive galaxy clusters with \mathrmlog(M_\mathrmhalo/M_⊙)\geqslant 14.8 at z = 0. These results suggest that QO-1000 is a more mature protocluster than the other known protoclusters. It is likely in a transition phase between star-forming protoclusters and quenched galaxy clusters.

14. ApJ

    

    An Atlas of Color-selected Quiescent Galaxies at z > 3 in Public JWST Fields

    Francesco Valentino, Gabriel Brammer, Katriona M. L. Gould, Vasily Kokorev, Seiji Fujimoto, and 22 more authors

    The Astrophysical Journal, Apr 2023

    Abs DOI

    We present the results of a systematic search for candidate quiescent galaxies in the distant universe in 11 JWST fields with publicly available observations collected during the first 3 months of operations and covering an effective sky area of \raisebox-0.5ex\textasciitilde145 arcmin^2. We homogeneously reduce the new JWST data and combine them with existing observations from the Hubble Space Telescope. We select a robust sample of \raisebox-0.5ex\textasciitilde80 candidate quiescent and quenching galaxies at 3 < z < 5 using two methods: (1) based on their rest-frame UVJ colors, and (2) a novel quantitative approach based on Gaussian mixture modeling of the near-UV - U, U - V, and V - J rest-frame color space, which is more sensitive to recently quenched objects. We measure comoving number densities of massive (M _\ensuremath⋆ \ensuremath≥ 10^10.6 M _\ensuremath⊙) quiescent galaxies consistent with previous estimates relying on ground-based observations, after homogenizing the results in the literature with our mass and redshift intervals. However, we find significant field-to-field variations of the number densities up to a factor of 2-3, highlighting the effect of cosmic variance and suggesting the presence of overdensities of red quiescent galaxies at z > 3, as could be expected for highly clustered massive systems. Importantly, JWST enables the robust identification of quenching/quiescent galaxy candidates at lower masses and higher redshifts than before, challenging standard formation scenarios. All data products, including the literature compilation, are made publicly available.

15. ApJL

    

    JWST Reveals a Population of Ultrared, Flattened Galaxies at 2 ≲ z ≲ 6 Previously Missed by HST

    Erica J. Nelson, Katherine A. Suess, Rachel Bezanson, Sedona H. Price, Pieter van Dokkum, and 21 more authors

    The Astrophysical Journal Letters, May 2023

    Abs DOI

    With just a month of data, JWST is already transforming our view of the universe, revealing and resolving starlight in unprecedented populations of galaxies. Although “HST-dark” galaxies have previously been detected at long wavelengths, these observations generally suffer from a lack of spatial resolution, which limits our ability to characterize their sizes and morphologies. Here we report on a first view of starlight from a subset of the HST- dark population that is bright with JWST/NIRCam (4.4 \ensuremathμm < 24.5 mag) and very faint or even invisible with HST (<1.6 \ensuremathμm). In this Letter we focus on a dramatic and unanticipated population of physically extended galaxies (\ensuremath≳0.″25). These 12 galaxies have photometric redshifts 2 < z < 6, high stellar masses M _\ensuremath⋆ \ensuremath≳ 10^10 M _\ensuremath⊙, and significant dust-attenuated star formation. Surprisingly, the galaxies have elongated projected axis ratios at 4.4 \ensuremathμm, suggesting that the population is disk dominated or prolate and we hence refer to them as ultrared flattened objects. Most of the galaxies appear red at all radii, suggesting significant dust attenuation throughout. With R _e (F444W) \raisebox-0.5ex~1-2 kpc, the galaxies are similar in size to compact massive galaxies at z \raisebox-0.5ex~2 and the cores of massive galaxies and S0s at z \raisebox-0.5ex~0. The stellar masses, sizes, and morphologies of the sample suggest that some could be progenitors of lenticular or fast-rotating galaxies in the local universe. The existence of this population suggests that our previous censuses of the universe may have missed massive, dusty edge-on disks, in addition to dust- obscured starbursts.

16. ApJL

    

    The Earliest Stage of Galactic Star Formation

    Charles L. Steinhardt, Vadim Rusakov, Thomas H. Clark, Andrei Diaconu, John Forbes, and 3 more authors

    The Astrophysical Journal Letters, Jun 2023

    Abs DOI

    Using a recently developed technique to estimate gas temperatures (T _SF) in star-forming regions from large photometric surveys, we propose a diagram, analogous to the Hertzsprung-Russell diagram for individual stars, to probe the evolution of individual galaxies. On this T _SF-sSFR (specific star formation rate) diagram, a small fraction of star-forming galaxies appear to be dominated by different feedback mechanisms than typical star-forming galaxies. These galaxies generically have younger stellar populations and lower stellar masses and increase in relative abundance toward higher redshifts, so we argue that these objects are in an earlier stage of galactic star formation. Further, Hubble observations find that these “core-forming” galaxies also exhibit distinct morphology and that tracks on the T _SF-sSFR diagram are also a morphological sequence. Thus, unlike starburst phases which can be triggered environmentally, these earliest core-forming galaxies appear to be a stage that typical galaxies go through early in their star formation history. We therefore argue that most galaxies first go through a core formation stage, then subsequently disk formation, and finally become quiescent.

17. ApJ

    

    Introducing the Texas Euclid Survey for Lyα (TESLA) Survey: Initial Study Correlating Galaxy Properties to Lyα Emission

    Óscar A. Chávez Ortiz, Steven L. Finkelstein, Dustin Davis, Gene Leung, Erin Mentuch Cooper, and 24 more authors

    The Astrophysical Journal, Aug 2023

    Abs DOI

    We present the Texas Euclid Survey for Ly\ensuremathα (TESLA), a spectroscopic survey in the 10 deg^2 of the Euclid North Ecliptic Pole (NEP) field. Using TESLA, we study how the physical properties of Ly\ensuremathα emitters (LAEs) correlate with Ly\ensuremathα emission to understand the escape of Ly\ensuremathα emission from galaxies at redshifts of 2-3.5. We present an analysis of 43 LAEs performed in the NEP field using early data from the TESLA survey. We use Subaru Hyper Suprime-Cam imaging in the grizy bands, Spitzer/IRAC channels 1 and 2 from the Hawaii 20 deg^2 (H20) survey, and spectra acquired by the Visible Integral-Field Replicable Unit Spectrograph (VIRUS) on the Hobby-Eberly Telescope. We perform spectral energy distribution (SED) fitting to compute the galaxy properties of 43 LAEs, and study correlations between stellar mass, star formation rate (SFR), and dust to the Ly\ensuremathα rest-frame equivalent width (W _Ly\ensuremathα ). We uncover marginal (1\ensuremathσ significance) correlations between stellar mass and W _Ly\ensuremathα , and SFR and W _Ly\ensuremathα , with a Spearman correlation coefficient of -0. 34_-.14^+.17 and -0. 37_-.14^+.16 , respectively. We show that the W _Ly\ensuremathα distribution of the 43 LAEs is consistent with being drawn from an exponential distribution with an e-folding scale of W _0 = 150 Å. Once complete the TESLA survey will enable the study of \ensuremath≳50,000 LAEs to explore more correlations between galaxy properties and W _Ly\ensuremathα . The large sample size will allow the construction of a predictive model for W _Ly\ensuremathα as a function of SED-derived galaxy properties, which could be used to improve Ly\ensuremathα-based constraints on reionization.

18. ApJ

    

    JWST UNCOVER: Extremely Red and Compact Object at z _phot ≃ 7.6 Triply Imaged by A2744

    Lukas J. Furtak, Adi Zitrin, Adèle Plat, Seiji Fujimoto, Bingjie Wang, and 27 more authors

    The Astrophysical Journal, Aug 2023

    Abs DOI

    Recent JWST/NIRCam imaging taken for the ultra-deep UNCOVER program reveals a very red dropout object at z _phot ≃ 7.6, triply imaged by the galaxy cluster A2744 (z _d = 0.308). All three images are very compact, i.e., unresolved, with a delensed size upper limit of r _ e \ensuremath≲ 35 pc. The images have apparent magnitudes of m _F444W \raisebox-0.5ex~25-26 AB, and the magnification-corrected absolute UV magnitude of the source is M _UV,1450 = -16.81 \ensuremath\pm 0.09. From the sum of observed fluxes and from a spectral energy distribution (SED) analysis, we obtain estimates of the bolometric luminosities of the source of L _bol \ensuremath≳ 10^43 erg s^-1 and L _bol \raisebox-0.5ex~10^44-10^46 erg s^-1, respectively. Based on its compact, point-like appearance, its position in color-color space, and the SED analysis, we tentatively conclude that this object is a UV-faint dust-obscured quasar-like object, i.e., an active galactic nucleus at high redshift. We also discuss other alternative origins for the object’s emission features, including a massive star cluster, Population III, supermassive, or dark stars, or a direct-collapse black hole. Although populations of red galaxies at similar photometric redshifts have been detected with JWST, this object is unique in that its high-redshift nature is corroborated geometrically by lensing, that it is unresolved despite being magnified-and thus intrinsically even more compact-and that it occupies notably distinct regions in both size-luminosity and color-color space. Planned UNCOVER JWST/NIRSpec observations, scheduled in Cycle 1, will enable a more detailed analysis of this object.

19. ApJ

    

    COSMOS-Web: An Overview of the JWST Cosmic Origins Survey

    Caitlin M. Casey, Jeyhan S. Kartaltepe, Nicole E. Drakos, Maximilien Franco, Santosh Harish, and 81 more authors

    The Astrophysical Journal, Sep 2023

    Abs DOI

    We present the survey design, implementation, and outlook for COSMOS- Web, a 255 hr treasury program conducted by the James Webb Space Telescope in its first cycle of observations. COSMOS-Web is a contiguous 0.54 deg^2 NIRCam imaging survey in four filters (F115W, F150W, F277W, and F444W) that will reach 5\ensuremathσ point-source depths ranging \raisebox-0.5ex\textasciitilde27.5-28.2 mag. In parallel, we will obtain 0.19 deg^2 of MIRI imaging in one filter (F770W) reaching 5\ensuremathσ point-source depths of \raisebox-0.5ex\textasciitilde25.3-26.0 mag. COSMOS-Web will build on the rich heritage of multiwavelength observations and data products available in the COSMOS field. The design of COSMOS-Web is motivated by three primary science goals: (1) to discover thousands of galaxies in the Epoch of Reionization (6 \ensuremath≲ z \ensuremath≲ 11) and map reionization’s spatial distribution, environments, and drivers on scales sufficiently large to mitigate cosmic variance, (2) to identify hundreds of rare quiescent galaxies at z > 4 and place constraints on the formation of the universe’s most-massive galaxies (M _\ensuremath⋆ > 10^10 M _\ensuremath⊙), and (3) directly measure the evolution of the stellar-mass-to-halo-mass relation using weak gravitational lensing out to z \raisebox-0.5ex~2.5 and measure its variance with galaxies’ star formation histories and morphologies. In addition, we anticipate COSMOS- Web’s legacy value to reach far beyond these scientific goals, touching many other areas of astrophysics, such as the identification of the first direct collapse black hole candidates, ultracool subdwarf stars in the Galactic halo, and possibly the identification of z > 10 pair-instability supernovae. In this paper we provide an overview of the survey’s key measurements, specifications, goals, and prospects for new discovery.

20. ApJL

    

    UNCOVER: The Growth of the First Massive Black Holes from JWST/NIRSpec-Spectroscopic Redshift Confirmation of an X-Ray Luminous AGN at z = 10.1

    Andy D. Goulding, Jenny E. Greene, David J. Setton, Ivo Labbe, Rachel Bezanson, and 25 more authors

    The Astrophysical Journal Letters, Sep 2023

    Abs DOI

    The James Webb Space Telescope is now detecting early black holes (BHs) as they transition from “seeds” to supermassive BHs. Recently, Bogdan et al. reported the detection of an X-ray luminous supermassive BH, UHZ-1, with a photometric redshift at z > 10. Such an extreme source at this very high redshift provides new insights on seeding and growth models for BHs given the short time available for formation and growth. Harnessing the exquisite sensitivity of JWST/NIRSpec, here we report the spectroscopic confirmation of UHZ-1 at z = 10.073 \ensuremath\pm 0.002. We find that the NIRSpec/Prism spectrum is typical of recently discovered z \ensuremath≈ 10 galaxies, characterized primarily by star formation features. We see no clear evidence of the powerful X-ray source in the rest-frame UV/optical spectrum, which may suggest heavy obscuration of the central BH, in line with the Compton-thick column density measured in the X-rays. We perform a stellar population fit simultaneously to the new NIRSpec spectroscopy and previously available photometry. The fit yields a stellar-mass estimate for the host galaxy that is significantly better constrained than prior photometric estimates ( M_⋆∼1.4_-0.4^+0.3\times 10^8 M _\ensuremath⊙). Given the predicted BH mass (M _BH \raisebox-0.5ex~10^7-10^8 M _\ensuremath⊙), the resulting ratio of M _BH/M _\ensuremath⋆ remains 2 to 3 orders of magnitude higher than local values, thus lending support to the heavy seeding channel for the formation of supermassive BHs within the first billion years of cosmic evolution.

21. ApJ

    

    A Near-infrared-faint, Far-infrared-luminous Dusty Galaxy at z ∼ 5 in COSMOS-Web

    Jed McKinney, Sinclaire M. Manning, Olivia R. Cooper, Arianna S. Long, Hollis Akins, and 30 more authors

    The Astrophysical Journal, Oct 2023

    Abs DOI

    A growing number of far-infrared (FIR) bright sources completely invisible in deep extragalactic optical surveys hint at an elusive population of z > 4 dusty, star-forming galaxies. Cycle 1 JWST surveys are now detecting their rest-frame optical light, which provides key insight into their stellar properties and statistical constraints on the population as a whole. This work presents the JWST Near Infrared Camera (NIRCam) counterpart from the COSMOS-Web survey to an FIR SCUBA-2 and Atacama Large Millimeter/submillimeter Array (ALMA) source, AzTECC71, which was previously undetected at wavelengths shorter than 850 \ensuremathμm. AzTECC71, among the reddest galaxies in COSMOS-Web with F277W - F444W \raisebox-0.5ex~0.9, is undetected in NIRCam/F150W and F115W and fainter in F444W than other submillimeter galaxies identified in COSMOS-Web by 2-4 magnitudes. This is consistent with the system having both a lower stellar mass and higher redshift than the median dusty, star-forming galaxy. With deep ground- and space-based upper limits combined with detections in F277W, F444W, and the FIR including ALMA Band 6, we find a high probability (99%) that AzTECC71 is at z > 4 with z_\mathrmphot=5.7_-0.7^+0.8 . This galaxy is massive ( \mathrmlog\,M_* /M_⊙∼10.7 ) and infrared-luminous ( \mathrmlog\,L_\mathrmIR/L_⊙∼12.7 ), comparable to other optically undetected but FIR- bright dusty, star-forming galaxies at z > 4. This population of luminous, infrared galaxies at z > 4 is largely unconstrained but comprises an important bridge between the most extreme dust- obscured galaxies and more typical high-redshift star-forming galaxies. If further FIR-selected galaxies that drop out of the F150W filter in COSMOS-Web have redshifts z > 4 like AzTECC71, then the volume density of such sources may be \raisebox-0.5ex\textasciitilde3-10 \texttimes greater than previously estimated.

22. ApJL

    

    UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

    Vasily Kokorev, Seiji Fujimoto, Ivo Labbe, Jenny E. Greene, Rachel Bezanson, and 27 more authors

    The Astrophysical Journal Letters, Nov 2023

    Abs DOI

    Deep observations with the James Webb Space Telescope (JWST) have revealed an emerging population of red pointlike sources that could provide a link between the postulated supermassive black hole seeds and observed quasars. In this work, we present a JWST/NIRSpec spectrum from the JWST Cycle 1 UNCOVER Treasury survey of a massive accreting black hole at z = 8.50 displaying a clear broad-line component as inferred from the H\ensuremathβ line with FWHM = 3439 \ensuremath\pm 413 km s^-1, typical of the broad-line region of an active galactic nucleus (AGN). The AGN nature of this object is further supported by high ionization, as inferred from emission lines, and a point-source morphology. We compute a black hole mass of \mathrmlog_10(M_\mathrmBH/M_⊙)=8.17\pm 0.42 and a bolometric luminosity of L _bol \raisebox-0.5ex~6.6 \texttimes 10^45 erg s^-1. These values imply that our object is accreting at \raisebox-0.5ex\textasciitilde40% of the Eddington limit. Detailed modeling of the spectral energy distribution in the optical and near-infrared, together with constraints from ALMA, indicate an upper limit on the stellar mass of \mathrmlog_10(M_* /M_⊙) 8.7 , which would lead to an unprecedented ratio of black hole to host mass of at least \raisebox-0.5ex\textasciitilde30%. This is orders of magnitude higher compared to the local QSOs but consistent with recent AGN studies at high redshift with JWST. This finding suggests that a nonnegligible fraction of supermassive black holes either started out from massive seeds and/or grew at a super-Eddington rate at high redshift. Given the predicted number densities of high-z faint AGN, future NIRSpec observations of larger samples will allow us to further investigate galaxy-black hole coevolution in the early Universe.

23. ApJL

    

    UNCOVER: Illuminating the Early Universe-JWST/NIRSpec Confirmation of z > 12 Galaxies

    Bingjie Wang, Seiji Fujimoto, Ivo Labbé, Lukas J. Furtak, Tim B. Miller, and 22 more authors

    The Astrophysical Journal Letters, Nov 2023

    Abs DOI

    Observations of high-redshift galaxies provide a critical direct test to the theories of early galaxy formation, yet to date, only three have been spectroscopically confirmed at z > 12. Due to strong gravitational lensing over a wide area, the galaxy cluster field A2744 is ideal for searching for the earliest galaxies. Here we present JWST/NIRSpec observations of two galaxies: a robust detection at z_\mathrmspec=12.393_-0.001^+0.004 , and a plausible candidate at z_\mathrmspec=13.079_-0.001^+0.013 . The galaxies are discovered in JWST/NIRCam imaging and their distances are inferred with JWST/NIRSpec spectroscopy, all from the JWST Cycle 1 UNCOVER Treasury survey. Detailed stellar population modeling using JWST NIRCam and NIRSpec data corroborates the primeval characteristics of these galaxies: low mass (\raisebox-0.5ex~10^8 M _\ensuremath⊙), young, rapidly assembling, metal- poor, and star-forming. Interestingly, both galaxies are spatially resolved, having lensing-corrected rest-UV effective radii on the order of 300-400 pc, which are notably larger than other spectroscopically confirmed systems at similar redshifts. The observed dynamic range of z \ensuremath≳ 10 sizes spans over 1 order of magnitude, implying a significant scatter in the size-mass relation at early times. Deep into the epoch of reionization, these discoveries elucidate the emergence of the first galaxies.

24. ApJS

    

    The Farmer: A Reproducible Profile-fitting Photometry Package for Deep Galaxy Surveys

    J. R. Weaver, L. Zalesky, V. Kokorev, C. J. R. McPartland, N. Chartab, and 15 more authors

    The Astrophysical Journal Supplement Series, Nov 2023

    Abs DOI

    While space-borne optical and near-infrared facilities have succeeded in delivering a precise and spatially resolved picture of our Universe, their small survey area is known to underrepresent the true diversity of galaxy populations. Ground-based surveys have reached comparable depths but at lower spatial resolution, resulting in source confusion that hampers accurate photometry extractions. What once was limited to the infrared regime has now begun to challenge ground-based ultradeep surveys, affecting detection and photometry alike. Failing to address these challenges will mean forfeiting a representative view into the distant Universe. We introduce The Farmer: an automated, reproducible profile-fitting photometry package that pairs a library of smooth parametric models from The Tractor with a decision tree that determines the best-fit model in concert with neighboring sources. Photometry is measured by fitting the models on other bands leaving brightness free to vary. The resulting photometric measurements are naturally total, and no aperture corrections are required. Supporting diagnostics (e.g., \ensuremathχ ^2) enable measurement validation. As fitting models is relatively time intensive, The Farmer is built with high-performance computing routines. We benchmark The Farmer on a set of realistic COSMOS-like images and find accurate photometry, number counts, and galaxy shapes. The Farmer is already being utilized to produce catalogs for several large-area deep extragalactic surveys where it has been shown to tackle some of the most challenging optical and near-infrared data available, with the promise of extending to other ultradeep surveys expected in the near future. The Farmer is available to download from GitHub (https://github.com/astroweaver/the_farmer) and Zenodo (https://doi.org/10.5281/zenodo.8205817).

25. ApJS

    

    The Spitzer-HETDEX Exploratory Large-Area Survey. IV. Model-based Multiwavelength Photometric Catalog

    Gene C. K. Leung, Steven L. Finkelstein, John R. Weaver, Casey Papovich, Rebecca L. Larson, and 9 more authors

    The Astrophysical Journal Supplement Series, Dec 2023

    Abs DOI

    We present a 0.3-4.5 \ensuremathμm 16-band photometric catalog for the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers an \raisebox-0.5ex\textasciitilde27 deg^2 field within the footprint of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). Here we present new DECam imaging and an rizK _ s band-selected catalog of four million sources extracted using a fully model-based approach. We validate our photometry by comparing with the model-based DECam Legacy Survey. We analyze the differences between model-based and aperture photometry by comparing with the previous SHELA catalog, finding that our model-based photometry can measure point sources to fainter fluxes and better capture the full emission of resolved sources. The catalog is 80% (50%) complete at riz \raisebox-0.5ex~24.7 (25.1) AB mag, and the optical photometry reaches a 5\ensuremathσ depth of \raisebox-0.5ex\textasciitilde25.5 AB mag. We measure photometric redshifts and achieve a 1\ensuremathσ scatter of \ensuremath∆z/(1 + z) of 0.04 with available spectroscopic redshifts at 0 \ensuremath≤ z \ensuremath≤ 1. This large-area, multiwavelength photometric catalog, combined with spectroscopic information from HETDEX, will enable a wide range of extragalactic science investigations.

26. arXiv

    DUALZ: Deep UNCOVER-ALMA Legacy High-Z Survey

    Seiji Fujimoto, Rachel Bezanson, Ivo Labbe, Gabriel Brammer, Sedona H. Price, and 27 more authors

    arXiv, Sep 2023

    Abs DOI

    We present the survey design and initial results of the ALMA Cycle 9 program of DUALZ, which aims to establish a joint ALMA and JWST public legacy field targeting the massive galaxy cluster Abell 2744. DUALZ features a contiguous 4’\times6’ ALMA 30-GHz-wide mosaic in Band 6, covering areas of μ>2 down to a sensitivity of σ=32.7 \muJy. Through a blind search, we identified 69 dust continuum sources at S/N rsim5.0 with median redshift and intrinsic 1.2-mm flux of z=2.30 and S_\rm 1.2mm^\rm int=0.24\raisebox-0.5ex\textasciitildemJy. Of these, 27 have been spectroscopically confirmed, leveraged by the latest NIRSpec observations, while photometric redshift estimates are constrained by the comprehensive HST, NIRCam, and ALMA data for the remaining sources. With priors, we further identify a [CII]158 \mum line emitter at z=6.3254\pm0.0004, confirmed by the latest NIRSpec spectroscopy. The NIRCam counterparts of the 1.2-mm continuum exhibit undisturbed morphologies, denoted either by disk or spheroid, implying the triggers for the faint mm emission are less catastrophic than mergers. We have identified 8 HST-dark galaxies (F150W>27mag, F150W-F444W>2.3) and 2 JWST-dark (F444W>30mag) galaxy candidates among the ALMA continuum sources. The former includes face-on disk galaxies, hinting that substantial dust obscuration does not always result from inclination. We also detect a marginal dust emission from an X-ray-detected galaxy at z_\rm spec=10.07, suggesting an active co-evolution of the central black hole and its host. We assess the infrared luminosity function up to z\sim10 and find it consistent with predictions from galaxy formation models. To foster diverse scientific outcomes from the community, we publicly release reduced ALMA mosaic maps, cubes, and the source catalog.

27. MNRAS

    

    Unveiling the nature of infrared bright, optically dark galaxies with early JWST data

    L. Barrufet, P. A. Oesch, A. Weibel, G. Brammer, R. Bezanson, and 16 more authors

    Monthly Notices of the Royal Astronomical Society, Jun 2023

    Abs DOI

    Over the last few years, both Atacama Large Millimeter/submillimeter Array (ALMA) and Spitzer observations have revealed a population of likely massive galaxies at z > 3 that was too faint to be detected inHubble Space Telescope(HST) rest-frame ultraviolet imaging. However, due to the very limited photometry for individual galaxies, the true nature of these so-called HST-dark galaxies has remained elusive. Here, we present the first sample of such galaxies observed with very deep, high-resolution NIRCam imaging from the Early Release Science programme CEERS. 30 HST- dark sources are selected based on their red colours across 1.6-4.4 \mum. Their physical properties are derived from 12-band multiwavelength photometry, including ancillary HST imaging. We find that these galaxies are generally heavily dust- obscured (A_V \raisebox-0.5ex~2 mag), massive (log (M/M_\ensuremath⊙) \raisebox-0.5ex~10), star-forming sources at z \raisebox-0.5ex~2-8 with an observed surface density of \raisebox-0.5ex\textasciitilde0.8 arcmin^-2. This suggests that an important fraction of massive galaxies may have been missing from our cosmic census at z > 3 all the way into the Epoch of Reionization. The HST-dark sources lie on the main sequence of galaxies and add an obscured star formation rate density of \mathrm3.2^+1.8_-1.3 \times 10^-3 \,\rm M_⊙ yr^-1 Mpc^-3 at z \raisebox-0.5ex~7, showing likely presence of dust in the Epoch of Reionization. Our analysis shows the unique power of JWST to reveal this previously missing galaxy population and to provide a more complete census of galaxies at z = 2-8 based on rest-frame optical imaging.

28. MNRAS

    Correction to: Pilot-WINGS: An extended MUSE view of the structure of Abell 370

    David J. Lagattuta, Johan Richard, Franz Erik Bauer, Catherine Cerny, Adélaı̈de Claeyssens, and 20 more authors

    Monthly Notices of the Royal Astronomical Society, Jul 2023

    DOI
29. MNRAS

    

    UNCOVERing the extended strong lensing structures of Abell 2744 with the deepest JWST imaging

    Lukas J. Furtak, Adi Zitrin, John R. Weaver, Hakim Atek, Rachel Bezanson, and 16 more authors

    Monthly Notices of the Royal Astronomical Society, Aug 2023

    Abs DOI

    We present a new parametric lens model for the massive galaxy cluster Abell 2744 based on new ultra-deep JWST imaging taken in the framework of the UNCOVER program. These observations constitute the deepest JWST images of a lensing cluster to date, adding to existing deep Hubble Space Telescope (HST) images and the recent JWST Early Release Science and Director’s Discretionary Time data taken for this field. The wide field of view of UNCOVER (\raisebox-0.5ex\textasciitilde45 arcmin^2) extends beyond the cluster’s well-studied central core and reveals a spectacular wealth of prominent lensed features around two massive cluster sub-structures in the north and north-west, where no multiple images were previously known. We identify 75 new multiple images and candidates of 17 sources, 43 of which allow us, for the first time, to constrain the lensing properties and total mass distribution around these extended cluster structures using strong lensing (SL). Our model yields an effective Einstein radius of \ensuremathθ_E, main = 23.2 \ensuremath\pm 2.3 arcsec for the main cluster core (for z_s = 2), enclosing a mass of M(< \ensuremathθ_E, main) = (7.7 \ensuremath\pm 1.1) \texttimes 10^13 M_\ensuremath⊙, and \ensuremathθ_E, NW = 13.1 \ensuremath\pm 1.3 arcsec for the newly discovered north-western SL structure enclosing M(< \ensuremathθ_E, NW) = (2.2 \ensuremath\pm 0.3) \texttimes 10^13 M_\ensuremath⊙. The northern clump is somewhat less massive with \ensuremathθ_E, N = 7.4 \ensuremath\pm 0.7 arcsec enclosing M(< \ensuremathθ_E, N) = (0.8 \ensuremath\pm 0.1) \texttimes 10^13 M_\ensuremath⊙. We find the northern sub-structures of Abell 2744 to broadly agree with the findings from weak lensing analyses and align with the filamentary structure found by these previous studies. Our model in particular reveals a large area of high magnification values between the various cluster structures, which will be paramount for lensed galaxy studies in the UNCOVER field. The model is made publicly available to accompany the first UNCOVER data release.

30. MNRAS

    

    JWST UNCOVER: discovery of z > 9 galaxy candidates behind the lensing cluster Abell 2744

    Hakim Atek, Iryna Chemerynska, Bingjie Wang, Lukas J. Furtak, Andrea Weibel, and 17 more authors

    Monthly Notices of the Royal Astronomical Society, Oct 2023

    Abs DOI

    We present the results of a search for high-redshift (z > 9) galaxy candidates in the JWST UNCOVER survey, using deep NIRCam and NIRISS imaging in seven bands over \raisebox-0.5ex\textasciitilde45 arcmin^2 and ancillary Hubble Space Telescope (HST) observations. The NIRCam observations reach a 5\ensuremathσ limiting magnitude of \raisebox-0.5ex\textasciitilde29.2 AB. The identification of high-z candidates relies on a combination of a dropout selection and photometric redshifts. We find 16 candidates at 9 < z < 12 and three candidates at 12 < z < 13, eight candidates are deemed very robust. Their lensing amplification ranges from \ensuremathμ = 1.2 to 11.5. Candidates have a wide range of (lensing corrected) luminosities and young ages, with low stellar masses [6.8 < log(M_\ensuremath⋆/M_\ensuremath⊙) < 9.5] and low star formation rates (SFR = 0.2-7 M_\ensuremath⊙ yr^-1), confirming previous findings in early JWST observations of z > 9. A few galaxies at z \raisebox-0.5ex~9-10 appear to show a clear Balmer break between the F356W and F444W/F410M bands, which helps constrain their stellar mass. We estimate blue UV continuum slopes between \ensuremathβ = -1.8 and -2.3, typical for early galaxies at z > 9 but not as extreme as the bluest recently discovered sources. We also find evidence for a rapid redshift-evolution of the mass-luminosity relation and a redshift evolution of the UV continuum slope for a given range of intrinsic magnitude, in line with theoretical predictions. These findings suggest that deeper JWST observations are needed to reach the fainter galaxy population at those early epochs, and follow-up spectroscopy will help better constrain the physical properties and star formation histories of a larger sample of galaxies.

2022

1. A&A

   

   Euclid preparation. XVII. Cosmic Dawn Survey: Spitzer Space Telescope observations of the Euclid deep fields and calibration fields

   Euclid Collaboration, A. Moneti, H. J. McCracken, M. Shuntov, O. B. Kauffmann, and 193 more authors

   Astronomy & Astrophysics, Feb 2022

   Abs DOI

   We present a new infrared survey covering the three Euclid deep fields and four other Euclid calibration fields using Spitzer Space Telescope’s Infrared Array Camera (IRAC). We combined these new observations with all relevant IRAC archival data of these fields in order to produce the deepest possible mosaics of these regions. In total, these observations represent nearly 11 % of the total Spitzer Space Telescope mission time. The resulting mosaics cover a total of approximately 71.5 deg^2 in the 3.6 and 4.5 \ensuremathμm bands, and approximately 21.8 deg^2 in the 5.8 and 8 \ensuremathμm bands. They reach at least 24 AB magnitude (measured to 5\ensuremathσ, in a 2″.5 aperture) in the 3.6 \ensuremathμm band and up to \ensuremath∼5 mag deeper in the deepest regions. The astrometry is tied to the Gaia astrometric reference system, and the typical astrometric uncertainty for sources with 16 < [3.6]< 19 is \ensuremath≲0″.15. The photometric calibration is in excellent agreement with previous WISE measurements. We extracted source number counts from the 3.6 \ensuremathμm band mosaics, and they are in excellent agreement with previous measurements. Given that the Spitzer Space Telescope has now been decommissioned, these mosaics are likely to be the definitive reduction of these IRAC data. This survey therefore represents an essential first step in assembling multi- wavelength data on the Euclid deep fields, which are set to become some of the premier fields for extragalactic astronomy in the 2020s.

2. A&A

   

   COSMOS2020: Cosmic evolution of the stellar-to-halo mass relation for central and satellite galaxies up to z ∼ 5

   M. Shuntov, H. J. McCracken, R. Gavazzi, C. Laigle, J. R. Weaver, and 11 more authors

   Astronomy & Astrophysics, Aug 2022

   Abs DOI

   We used the COSMOS2020 catalog to measure the stellar-to-halo mass relation (SHMR) divided by central and satellite galaxies from z = 0.2 to z = 5.5. Starting from accurate photometric redshifts, we measured the near-infrared selected two-point angular correlation and stellar mass functions in ten redshift bins. We used a phenomenological model that parametrizes the stellar-to- halo mass relation for central galaxies and the number of galaxies inside each halo to describe our observations. This model qualitatively reproduces our measurements and their dependence on the stellar mass threshold. Surprisingly, the mean halo occupation distribution only shows a mild evolution with redshift suggesting that galaxies occupy halos similarly throughout cosmic time. At each redshift, we measured the ratio of stellar mass to halo mass, M_*/M_h, which shows the characteristic strong dependence of halo mass with a peak at M_h^peak \ensuremath∼ 2 \texttimes 10^12 M_\ensuremath⊙. For the first time, using a joint modeling of clustering and abundances, we measured the evolution of M_h^peak from z = 0.2 to z = 5.5. M_h^peak increases gradually with redshift from log M_h^peak/M_\ensuremath⊙ \ensuremath∼ 12.1 at z \ensuremath∼ 0.3 to log M_h^peak/M_\ensuremath⊙ \ensuremath∼ 12.3 at z \ensuremath∼ 2, and up to log M_h^peak/M_\ensuremath⊙ \ensuremath∼ 12.9 at z \ensuremath∼ 5. Similarly, the stellar mass peak M_\ensuremath*^peak increases with redshift from log M_\ensuremath*^peak/M_\ensuremath⊙ \ensuremath∼ 10.5 at z \ensuremath∼ 0.3 to log M_\ensuremath*^peak/M_\ensuremath⊙ \ensuremath∼ 10.9 at z \ensuremath∼ 3. The SHMR ratio at the peak halo mass remains almost constant with redshift. These results are in accordance with the scenario in which the peak of star-formation efficiency moves toward more massive halos at higher redshifts. We also measured the fraction of satellites as a function of stellar mass and redshift. For all stellar mass thresholds, the satellite fraction decreases at higher redshifts. At a given redshift, there is a higher fraction of low-mass satellites and this fraction reaches a plateau at \ensuremath∼25% at z \ensuremath∼ 1. The satellite contribution to the total stellar mass budget in halos becomes more important than that of the central at halo masses of about M_h > 10^13 M_\ensuremath⊙ and always stays below the peak, indicating that quenching mechanisms are present in massive halos that keep the star- formation efficiency low. Finally, we compared our results with three hydrodynamical simulations: HORIZON-AGN, TNG100 of the ILLUSTRISTNG project, and EAGLE. We find that the most significant discrepancy is at the high-mass end, where the simulations generally show that satellites have a higher contribution to the total stellar mass budget than the observations. This, together with the finding that the fraction of satellites is higher in the simulations, indicates that the feedback mechanisms acting in both group- and cluster-scale halos appear to be less efficient in quenching the mass assembly of satellites - and that quenching occurs much later in the simulations.

3. A&A

   

   Diagnosing deceivingly cold dusty galaxies at 3.5 < z < 6: A substantial population of compact starbursts with high infrared optical depths

   Shuowen Jin, Emanuele Daddi, Georgios E. Magdis, Daizhong Liu, John R. Weaver, and 7 more authors

   Astronomy & Astrophysics, Sep 2022

   Abs DOI

   Using NOEMA and ALMA 3mm line scans, we measured spectroscopic redshifts of six new dusty galaxies at 3.5 < z < 4.2 by solidly detecting [CI](1-0) and CO transitions. The sample was selected from the COSMOS and GOODS-North super-deblended catalogs with far- infrared (FIR) photometric redshifts z_phot > 6 based on template IR spectral energy distribution (SED) from known submillimeter galaxies at z = 4-6. Dust SED analyses explain the z_phot overestimate from seemingly cold dust temperatures (T_d) and steep Rayleigh-Jeans (RJ) slopes, providing additional examples of cold dusty galaxies impacted by the cosmic microwave background (CMB). We therefore studied the general properties of the enlarged sample of 10 “cold” dusty galaxies over 3.5 < z < 6. We conclude that these galaxies are deceivingly cold at the surface but are actually warm in their starbursting cores. Several lines of evidence support this scenario: (1) The high infrared surface density \ensuremathΣ_IR and cold T_d from optically thin models appear to violate the Stefan-Boltzmann law; (2) the gas masses derived from optically thin dust masses are inconsistent with estimates from dynamics and CI luminosities; (3) the implied high star formation efficiencies would conflict with cold T_d; and (4) high FIR optical depth is implied even using the lower, optically thick dust masses. This work confirms the existence of a substantial population of deceivingly cold, compact dusty starburst galaxies at z \ensuremath≳ 4, together with the severe impact of the CMB on their RJ observables, paving the way for the diagnostics of optically thick dust in the early Universe. Conventional gas mass estimates based on RJ dust continuum luminosities implicitly assume an optically thin case, which leads to overestimation of gas masses by a factor of 2-3 on average in compact dusty star-forming galaxies.

4. A&A

   

   COSMOS2020: Manifold learning to estimate physical parameters in large galaxy surveys

   I. Davidzon, K. Jegatheesan, O. Ilbert, S. de la Torre, S. K. Leslie, and 14 more authors

   Astronomy & Astrophysics, Sep 2022

   Abs DOI

   We present a novel method for estimating galaxy physical properties from spectral energy distributions (SEDs) as an alternative to template fitting techniques and based on self-organizing maps (SOMs) to learn the high-dimensional manifold of a photometric galaxy catalog. The method has previously been tested with hydrodynamical simulations in Davidzon et al. (2019, MNRAS, 489, 4817), however, here it is applied to real data for the first time. It is crucial for its implementation to build the SOM with a high-quality panchromatic data set, thus we selected “COSMOS2020” galaxy catalog for this purpose. After the training and calibration steps with COSMOS2020, other galaxies can be processed through SOMs to obtain an estimate of their stellar mass and star formation rate (SFR). Both quantities resulted in a good agreement with independent measurements derived from more extended photometric baseline and, in addition, their combination (i.e., the SFR vs. stellar mass diagram) shows a main sequence of star-forming galaxies that is consistent with the findings of previous studies. We discuss the advantages of this method compared to traditional SED fitting, highlighting the impact of replacing the usual synthetic templates with a collection of empirical SEDs built by the SOM in a “data-driven” way. Such an approach also allows, even for extremely large data sets, for an efficient visual inspection to identify photometric errors or peculiar galaxy types. While also considering the computational speed of this new estimator, we argue that it will play a valuable role in the analysis of oncoming large-area surveys such as Euclid of the Legacy Survey of Space and Time at the Vera C. Rubin Telescope.

5. A&A

   

   A galaxy group candidate at z ≈ 3.7 in the COSMOS field

   Nikolaj B. Sillassen, Shuowen Jin, Georgios E. Magdis, Emanuele Daddi, John R. Weaver, and 10 more authors

   Astronomy & Astrophysics, Sep 2022

   Abs DOI

   We report a galaxy group candidate HPC1001 at z \ensuremath≈ 3.7 in the COSMOS field. This structure was selected as a high galaxy overdensity at z > 3 in the COSMOS2020 catalog. It contains ten candidate members, of which eight are assembled in a 10″ \texttimes 10″ area with the highest sky density among known protoclusters and groups at z > 3. Four out of ten sources were also detected at 1.2 mm with Atacama Large Millimeter Array continuum observations. Photometric redshifts, measured by four independent methods, fall within a narrow range of 3.5 < z < 3.9 and with a weighted average of z = 3.65 \ensuremath\pm 0.07. The integrated far-IR-to-radio spectral energy distribution yields a total UV and IR star formation rate SFR \ensuremath≈ 900 M_\ensuremath⊙ yr^\ensuremath-1. We also estimated a halo mass of \ensuremath∼10^13 M_\ensuremath⊙ for the structure, which at this redshift is consistent with potential cold gas inflow. Remarkably, the most massive member has a specific star formation rate and dust to stellar mass ratio of M_dust/M_* that are both significantly lower than that of star-forming galaxies at this redshift, suggesting that HPC1001 could be a z \ensuremath≈ 3.7 galaxy group in maturing phase. If confirmed, this would be the earliest structure in maturing phase to date, and an ideal laboratory to study the formation of the earliest quiescent galaxies as well as cold gas accretion in dense environments.

6. A&A

   

   Euclid preparation. XXI. Intermediate-redshift contaminants in the search for z > 6 galaxies within the Euclid Deep Survey

   S. E. van Mierlo, K. I. Caputi, M. Ashby, H. Atek, M. Bolzonella, and 195 more authors

   Astronomy & Astrophysics, Oct 2022

   Abs DOI

   Context. The Euclid mission is expected to discover thousands of z > 6 galaxies in three deep fields, which together will cover a \ensuremath∼50 deg^2 area. However, the limited number of Euclid bands (four) and the low availability of ancillary data could make the identification of z > 6 galaxies challenging. \Aims: In this work we assess the degree of contamination by intermediate-redshift galaxies (z = 1-5.8) expected for z > 6 galaxies within the Euclid Deep Survey. \Methods: This study is based on \ensuremath∼176 000 real galaxies at z = 1-8 in a \ensuremath∼0.7 deg^2 area selected from the UltraVISTA ultra-deep survey and \ensuremath∼96 000 mock galaxies with 25.3 \ensuremath≤ H < 27.0, which altogether cover the range of magnitudes to be probed in the Euclid Deep Survey. We simulate Euclid and ancillary photometry from fiducial 28-band photometry and fit spectral energy distributions to various combinations of these simulated data. \Results: We demonstrate that identifying z > 6 galaxies with Euclid data alone will be very effective, with a z > 6 recovery of 91% (88%) for bright (faint) galaxies. For the UltraVISTA-like bright sample, the percentage of z = 1-5.8 contaminants amongst apparent z > 6 galaxies as observed with Euclid alone is 18%, which is reduced to 4% (13%) by including ultra-deep Rubin (Spitzer) photometry. Conversely, for the faint mock sample, the contamination fraction with Euclid alone is considerably higher at 39%, and minimised to 7% when including ultra-deep Rubin data. For UltraVISTA-like bright galaxies, we find that Euclid (I_E \ensuremath- Y_E) > 2.8 and (Y_E \ensuremath- J_E) < 1.4 colour criteria can separate contaminants from true z > 6 galaxies, although these are applicable to only 54% of the contaminants as many have unconstrained (I_E \ensuremath- Y_E) colours. In the best scenario, these cuts reduce the contamination fraction to 1% whilst preserving 81% of the fiducial z > 6 sample. For the faint mock sample, colour cuts are infeasible; we find instead that a 5\ensuremathσ detection threshold requirement in at least one of the Euclid near-infrared bands reduces the contamination fraction to 25%.

7. A&A

   

   COSMOS2020: UV-selected galaxies at z ≥ 7.5

   O. B. Kauffmann, O. Ilbert, J. R. Weaver, H. J. McCracken, B. Milvang-Jensen, and 14 more authors

   Astronomy & Astrophysics, Nov 2022

   Abs DOI

   This paper presents a new search for z \ensuremath≥ 7.5 galaxies using the COSMOS2020 photometric catalogues. Finding galaxies at the reionisation epoch through deep imaging surveys remains observationally challenging. The larger area covered by ground- based surveys such as COSMOS enables the discovery of the brightest galaxies at these high redshifts. Covering 1.4 deg^2, our COSMOS catalogues were constructed from the latest UltraVISTA data release (DR4) combined with the final Spitzer/IRAC COSMOS images and the Hyper-Suprime-Cam Subaru Strategic Program DR2 release. We identified 17 new 7.5 < z < 10 candidate sources, and confirm 15 previously published candidates. Using deblended photometry extracted by fitting surface brightness models on multi-band images, we selected four candidates which would be rejected using fixed aperture photometry. We tested the robustness of all our candidates by comparing six different photometric redshift estimates. Finally, we computed the galaxy UV luminosity function in three redshift bins centred at z = 8, 9, 10. We find no clear evolution of the number density of the brightest galaxies M_UV < \ensuremath-21.5, in agreement with previous works. Rapid changes in the quenching efficiency or attenuation by dust could explain such a lack of evolution between z \ensuremath∼ 8 and z \ensuremath∼ 9. A spectroscopic confirmation of the redshifts, already planned with JWST and the Keck telescopes, will be essential to confirm our results.

8. ApJ

   

   COSMOS2020: Ubiquitous AGN Activity of Massive Quiescent Galaxies at 0 < z < 5 Revealed by X-Ray and Radio Stacking

   Kei Ito, Masayuki Tanaka, Takamitsu Miyaji, Olivier Ilbert, Olivier B. Kauffmann, and 6 more authors

   The Astrophysical Journal, Apr 2022

   Abs DOI

   We characterize the average X-ray and radio properties of quiescent galaxies (QGs) with \mathrmlog(M_⋆/M_⊙) 10 at 0 < z < 5. QGs are photometrically selected from the latest COSMOS2020 catalog. We conduct the stacking analysis of X-ray images of the Chandra COSMOS Legacy Survey for individually undetected QGs. Thanks to the large sample and deep images, the stacked X-ray signal is significantly detected up to z \raisebox-0.5ex~5. The average X-ray luminosity cannot be explained by the X-ray luminosity of X-ray binaries, suggesting that the low-luminosity active galactic nuclei (AGNs) ubiquitously exist in QGs. Moreover, the X-ray AGN luminosity of QGs at z > 1.5 is higher than that of star-forming galaxies (SFGs), derived in the same manner as QGs. The stacking analysis of the VLA-COSMOS images is conducted for the identical sample, and the radio signal for QGs is also detected up to z \raisebox-0.5ex~5. We find that the radio AGN luminosity of QGs at z > 1.5 is also higher than SFGs, which is in good agreement with the X-ray analysis. The enhanced AGN activity in QGs suggested by the individual analysis in the X-ray and radio wavelength supports its important role for quenching at high redshift. Their enhanced AGN activity is less obvious at z < 1.5, which can be interpreted as an increasing role of others at lower redshifts, such as environmental quenching.

9. ApJ

   

   Joint Survey Processing. I. Compact Oddballs in the COSMOS Field-Low-luminosity Quasars at z > 6?

   Andreas L. Faisst, Ranga Ram Chary, Sergio Fajardo-Acosta, Roberta Paladini, Benjamin Rusholme, and 6 more authors

   The Astrophysical Journal, Apr 2022

   Abs DOI

   The faint-end slope of the quasar luminosity function at z \raisebox-0.5ex~6 and its implication on the role of quasars in reionizing the intergalactic medium at early times has been an outstanding problem for some time. The identification of faint high-redshift quasars with luminosities of <10^44.5 erg s^-1 is challenging. They are rare (few per square degree), and the separation of these unresolved quasars from late-type stars and compact star-forming galaxies is difficult from ground-based observations alone. In addition, source confusion becomes significant at >25 mag, with \raisebox-0.5ex\textasciitilde30% of sources having their flux contaminated by foreground objects when the seeing resolution is \raisebox-0.5ex\textasciitilde0″.7. We mitigate these issues by performing a pixel-level joint processing of ground and space-based data from Subaru/Hyper-SuprimeCam (HSC) and Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). We create a deconfused catalog over the 1.64 deg^2 of the COSMOS field, after accounting for spatial varying point- spread functions and astrometric differences between the two data sets. We identify twelve low-luminosity (M _ UV \raisebox-0.5ex~-21 mag) z > 6 quasar candidates through (i) their red color measured between ACS/F814W and HSC/i band and (ii) their compactness in the space-based data. Nondetections of our candidates in Hubble DASH data argues against contamination from late-type stars. Our constraints on the faint end of the quasar luminosity function at z \raisebox-0.5ex~6.4 suggest a negligibly small contribution to reionization compared to the star-forming galaxy population. The confirmation of our candidates and the evolution of number density with redshift could provide better insights into how supermassive galaxies grew in the first billion years of cosmic time.

10. ApJL

    

    The Archival Discovery of a Strong Lyα and [C II] Emitter at z = 7.677

    Francesco Valentino, Gabriel Brammer, Seiji Fujimoto, Kasper E. Heintz, John R. Weaver, and 6 more authors

    The Astrophysical Journal Letters, Apr 2022

    Abs DOI

    We report the archival discovery of Ly\ensuremathα emission from the bright ultraviolet galaxy Y002 at z = 7.677, spectroscopically confirmed by its ionized carbon [C II] 158 \ensuremathμm emission line. The Ly\ensuremathα line is spatially associated with the rest-frame UV stellar emission (M _UV \raisebox-0.5ex~-22, 2\texttimes brighter than M_\mathrmUV^⋆ ), and it appears offset from the peak of the extended [C II] emission at the current \raisebox-0.5ex\textasciitilde1″ spatial resolution. We derive an estimate of the unobscured SFR_UV = (22 \ensuremath\pm 1) M _\ensuremath⊙ yr^-1 and set an upper limit of SFR_IR < 15 M _\ensuremath⊙ yr^-1 from the far-infrared (FIR) wavelength range, which globally places Y002 on the SFR(UV+IR)-L _[C II] correlation observed at lower redshifts. In terms of velocity, the peak of the Ly\ensuremathα emission is redshifted by \ensuremath∆v _Ly\ensuremathα \raisebox-0.5ex~500 km s^-1 from the systemic redshift set by [C II] and a high-velocity tail extends up to \raisebox-0.5ex\textasciitilde1000 km s^-1. The velocity offset is up to \raisebox-0.5ex\textasciitilde3.5\texttimes higher than the average estimate for similarly UV-bright emitters at z \raisebox-0.5ex~6-7, which might suggest that we are witnessing the merging of two clumps. A combination of strong outflows and the possible presence of an extended ionized bubble surrounding Y002 would likely facilitate the escape of copious Ly\ensuremathα light, as indicated by the large equivalent width EW_0(Ly\ensuremathα) \,=\,24_-6^+5 Å. Assuming that [C II] traces the neutral hydrogen, we estimate a H I gas fraction of M _H I/M _\ensuremath⋆ \ensuremath≳ 8 for Y002 as a system and speculate that patches of high H I column densities could contribute to explaining the observed spatial offsets between Ly\ensuremathα- and [C II]-emitting regions. The low dust content, implied by the nondetection of the FIR continuum emission at rest frame \raisebox-0.5ex\textasciitilde160 \ensuremathμm, would be sufficient to absorb any potential Ly\ensuremathα photons produced within the [C II] clump as a result of large H I column densities.

11. ApJ

    

    Implications of a Temperature-dependent Initial Mass Function. I. Photometric Template Fitting

    Albert Sneppen, Charles L. Steinhardt, Hagan Hensley, Adam S. Jermyn, Basel Mostafa, and 1 more author

    The Astrophysical Journal, May 2022

    Abs DOI

    A universal stellar initial mass function (IMF) should not be expected from theoretical models of star formation, but little conclusive observational evidence for a variable IMF has been uncovered. In this paper, a parameterization of the IMF is introduced into photometric template fitting of the COSMOS2015 catalog. The resulting best-fit templates suggest systematic variations in the IMF, with most galaxies exhibiting top-heavier stellar populations than in the Milky Way. At fixed redshift, only a small range of IMFs are found, with the typical IMF becoming progressively top-heavier with increasing redshift. Additionally, subpopulations of ULIRGs, quiescent and star- forming galaxies are compared with predictions of stellar population feedback and show clear qualitative similarities to the evolution of dust temperatures.

12. ApJ

    

    Implications of a Temperature-dependent Initial Mass Function. II. An Updated View of the Star-forming Main Sequence

    Charles L. Steinhardt, Albert Sneppen, Basel Mostafa, Hagan Hensley, Adam S. Jermyn, and 9 more authors

    The Astrophysical Journal, May 2022

    Abs DOI

    The stellar initial mass function (IMF) is predicted to depend upon the temperature of gas in star-forming molecular clouds. The introduction of an additional parameter, T _IMF, into photometric template fitting, allows galaxies to be fit with a range of IMFs. Three surprising new features appear: (1) most star-forming galaxies are best fit with a bottom-lighter IMF than the Milky Way; (2) most star-forming galaxies at fixed redshift are fit with a very similar IMF; and (3) the most- massive star-forming galaxies at fixed redshift instead exhibit a less bottom-light IMF, similar to that measured in quiescent galaxies. Additionally, since stellar masses and star formation rates both depend on the IMF, these results slightly modify the resulting relationship, while yielding similar qualitative characteristics to previous studies.

13. ApJ

    

    Implications of a Temperature-dependent Initial Mass Function. III. Mass Growth and Quiescence

    Charles L. Steinhardt, Albert Sneppen, Hagan Hensley, Adam S. Jermyn, Basel Mostafa, and 8 more authors

    The Astrophysical Journal, Jul 2022

    Abs DOI

    The stellar initial mass function (IMF) is predicted to depend upon the temperature of gas in star-forming molecular clouds. The introduction of an additional parameter, T _IMF, into photometric template fitting suggests most galaxies obey an IMF top heavier than the Galactic IMF. The implications of the revised fit on mass function, quiescence, and turnoff are discussed. At all redshifts, the highest-mass galaxies become quiescent first with the turnoff mass decreasing toward the present. The synchronous turnoff mass across galaxies suggests quiescence is driven by universal mechanisms rather than by stochastic or environmental processes.

14. ApJL

    

    Rest-frame Near-infrared Sizes of Galaxies at Cosmic Noon: Objects in JWST’s Mirror Are Smaller than They Appeared

    Katherine A. Suess, Rachel Bezanson, Erica J. Nelson, David J. Setton, Sedona H. Price, and 9 more authors

    The Astrophysical Journal Letters, Oct 2022

    Abs DOI

    Galaxy sizes and their evolution over cosmic time have been studied for decades and serve as key tests of galaxy formation models. However, at z \ensuremath≳ 1 these studies have been limited by a lack of deep, high-resolution rest-frame infrared imaging that accurately traces stellar mass distributions. Here, we leverage the new capabilities of the James Webb Space Telescope (JWST) to measure the 4.4 \ensuremathμm sizes of \raisebox-0.5ex\textasciitilde1000 galaxies with \mathrmlogM_* /M_⊙\geqslant 9 and 1.0 \ensuremath≤ z \ensuremath≤ 2.5 from public CEERS imaging in the Extended Groth Strip deep field. We compare the sizes of galaxies measured from NIRCam imaging at 4.4 \ensuremathμm (\ensuremathλ _rest \raisebox-0.5ex~1.6 \ensuremathμm) with sizes measured at 1.5 \ensuremathμm (\ensuremathλ _rest \raisebox-0.5ex~5500 Å). We find that, on average, galaxy half-light radii are \raisebox-0.5ex\textasciitilde9% smaller at 4.4 \ensuremathμm than 1.5 \ensuremathμm in this sample. This size difference is markedly stronger at higher stellar masses and redder rest-frame V - J colors: galaxies with M _* \raisebox-0.5ex~10^11 M _\ensuremath⊙ have 4.4 \ensuremathμm sizes that are \raisebox-0.5ex\textasciitilde30% smaller than their 1.5 \ensuremathμm sizes. Our results indicate that galaxy mass profiles are significantly more compact than their rest- frame optical light profiles at cosmic noon, and demonstrate that spatial variations in age and attenuation are important, particularly for massive galaxies. The trend we find here impacts our understanding of the size growth and evolution of galaxies, and suggests that previous studies based on rest-frame optical light may not have captured the mass-weighted structural evolution of galaxies. This paper represents a first step toward a new understanding of the morphologies of early massive galaxies enabled by JWST’s infrared window into the distant universe.

15. ApJL

    

    Two Remarkably Luminous Galaxy Candidates at z ≈ 10-12 Revealed by JWST

    Rohan P. Naidu, Pascal A. Oesch, Pieter van Dokkum, Erica J. Nelson, Katherine A. Suess, and 20 more authors

    The Astrophysical Journal Letters, Nov 2022

    Abs DOI

    The first few 100 Myr at z > 10 mark the last major uncharted epoch in the history of the universe, where only a single galaxy (GN-z11 at z \ensuremath≈ 11) is currently spectroscopically confirmed. Here we present a search for luminous z > 10 galaxies with JWST/NIRCam photometry spanning \ensuremath≈1-5 \ensuremathμm and covering 49 arcmin^2 from the public JWST Early Release Science programs (CEERS and GLASS). Our most secure candidates are two M _UV \ensuremath≈ -21 systems: GLASS-z12 and GLASS-z10. These galaxies display abrupt \ensuremath≳1.8 mag breaks in their spectral energy distributions (SEDs), consistent with complete absorption of flux bluewards of Ly\ensuremathα that is redshifted to z=12.4_-0.3^+0.1 and z=10.4_-0.5^+0.4 . Lower redshift interlopers such as quiescent galaxies with strong Balmer breaks would be comfortably detected at >5\ensuremathσ in multiple bands where instead we find no flux. From SED modeling we infer that these galaxies have already built up \raisebox-0.5ex~10^9 solar masses in stars over the \ensuremath≲300-400 Myr after the Big Bang. The brightness of these sources enable morphological constraints. Tantalizingly, GLASS-z10 shows a clearly extended exponential light profile, potentially consistent with a disk galaxy of r _50 \ensuremath≈ 0.7 kpc. These sources, if confirmed, join GN-z11 in defying number density forecasts for luminous galaxies based on Schechter UV luminosity functions, which require a survey area >10\texttimes larger than we have studied here to find such luminous sources at such high redshifts. They extend evidence from lower redshifts for little or no evolution in the bright end of the UV luminosity function into the cosmic dawn epoch, with implications for just how early these galaxies began forming. This, in turn, suggests that future deep JWST observations may identify relatively bright galaxies to much earlier epochs than might have been anticipated.

16. ApJ

    

    Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past

    Justin Atsushi Otter, Kate Rowlands, Katherine Alatalo, Ho-Hin Leung, Vivienne Wild, and 22 more authors

    The Astrophysical Journal, Dec 2022

    Abs DOI

    Post-starburst (PSB) galaxies have recently and rapidly quenched their star formation; thus, they are an important way to understand how galaxies transition from star-forming late types to quiescent early types. The recent discovery of large cold gas reservoirs in PSB galaxies calls into question the theory that galaxies must lose their gas to become quiescent. Optical Integral Field Spectroscopy (IFS) surveys have revealed two classes of PSB galaxies: central PSB (cPSB) galaxies with central quenching regions and ring PSB (rPSB) galaxies with quenching in their outskirts. We analyze a sample of 13 nearby (z < 0.1) PSB galaxies with spatially resolved optical IFS data from the Mapping Nearby Galaxies at Apache Point Observatory survey and matched resolution Atacama Large Millimeter/submillimeter Array observations of ^12CO(1-0). Disturbed stellar kinematics in 7/13 of our PSB galaxies and centrally concentrated molecular gas is consistent with a recent merger for most of our sample. In galaxies without merger evidence, alternate processes may funnel gas inward and suppress star formation, which may include outflows, stellar bars, and minor mergers or interactions. The star formation efficiencies of the PSB regions in nearly half our galaxies are suppressed while the gas fractions are consistent with star-forming galaxies. Active galactic nucleus (AGN) feedback may drive this stabilization, and we observe AGN-consistent emission in the centers of 5/13 galaxies. Finally, our cPSB and rPSB galaxies have similar properties except the ionized and molecular gas in cPSB galaxies is more disturbed. Overall, the molecular gas in our PSB galaxies tends to be compact and highly disturbed, resulting in concentrated gas reservoirs unable to form stars efficiently.

17. ApJL

    

    Early JWST Imaging Reveals Strong Optical and NIR Color Gradients in Galaxies at z 2 Driven Mostly by Dust

    Tim B. Miller, Katherine E. Whitaker, Erica J. Nelson, Pieter van Dokkum, Rachel Bezanson, and 5 more authors

    The Astrophysical Journal Letters, Dec 2022

    Abs DOI

    Recent studies have shown that galaxies at cosmic noon are redder in the center and bluer in the outskirts, mirroring results in the local universe. These color gradients could be caused by gradients in either the stellar age or dust opacity; however, distinguishing between these two causes is impossible with rest- frame optical photometry alone. Here we investigate the underlying causes of the gradients from spatially resolved rest- frame U - V versus V - J color-color diagrams measured from early observations with the James Webb Space Telescope. We use 1-4 \ensuremathμm NIRCam photometry from the CEERS survey of a sample of 54 galaxies with \mathrmlogM_* /M_⊙ 10 at redshifts 1.7 < z < 2.3 selected from the 3D-HST catalog. We model the light profiles in the F115W, F200W, and F356W NIRCam bands using imcascade, a Bayesian implementation of the multi-Gaussian expansion technique that flexibly represents galaxy profiles using a series of Gaussians. We construct resolved rest-frame U - V and V - J color profiles. The majority of star-forming galaxies have negative gradients (i.e., redder in the center, bluer in the outskirts) in both U - V and V - J colors consistent with radially decreasing dust attenuation. A smaller population (roughly 15%) of star-forming galaxies have positive U - V but negative V - J gradients implying centrally concentrated star formation. For quiescent galaxies, we find a diversity of UVJ color profiles, with roughly one-third showing star formation in their center. This study showcases the potential of JWST to study the resolved stellar populations of galaxies at cosmic noon.

18. ApJS

    

    COSMOS2020: A Panchromatic View of the Universe to z∼10 from Two Complementary Catalogs

    J. R. Weaver, O. B. Kauffmann, O. Ilbert, H. J. McCracken, A. Moneti, and 53 more authors

    The Astrophysical Journal Supplement Series, Jan 2022

    Abs DOI

    The Cosmic Evolution Survey (COSMOS) has become a cornerstone of extragalactic astronomy. Since the last public catalog in 2015, a wealth of new imaging and spectroscopic data have been collected in the COSMOS field. This paper describes the collection, processing, and analysis of these new imaging data to produce a new reference photometric redshift catalog. Source detection and multiwavelength photometry are performed for 1.7 million sources across the 2 deg^2 of the COSMOS field, \raisebox-0.5ex\textasciitilde966,000 of which are measured with all available broadband data using both traditional aperture photometric methods and a new profile-fitting photometric extraction tool, THE FARMER, which we have developed. A detailed comparison of the two resulting photometric catalogs is presented. Photometric redshifts are computed for all sources in each catalog utilizing two independent photometric redshift codes. Finally, a comparison is made between the performance of the photometric methodologies and of the redshift codes to demonstrate an exceptional degree of self-consistency in the resulting photometric redshifts. The i < 21 sources have subpercent photometric redshift accuracy and even the faintest sources at 25 < i < 27 reach a precision of 5%. Finally, these results are discussed in the context of previous, current, and future surveys in the COSMOS field. Compared to COSMOS2015, it reaches the same photometric redshift precision at almost one magnitude deeper. Both photometric catalogs and their photometric redshift solutions and physical parameters will be made available through the usual astronomical archive systems (ESO Phase 3, IPAC-IRSA, and CDS).

19. ApJS

    

    ALMA Lensing Cluster Survey: Hubble Space Telescope and Spitzer Photometry of 33 Lensed Fields Built with CHArGE

    V. Kokorev, G. Brammer, S. Fujimoto, K. Kohno, G. E. Magdis, and 28 more authors

    The Astrophysical Journal Supplement Series, Dec 2022

    Abs DOI

    We present a set of multiwavelength mosaics and photometric catalogs in the Atacama Large Millimeter/submillimeter Array (ALMA) lensing cluster survey fields. The catalogs were built by the reprocessing of archival data from the Complete Hubble Archive for Galaxy Evolution compilation, taken by the Hubble Space Telescope (HST) in the Reionization Lensing Cluster Survey, Cluster Lensing And Supernova survey with Hubble, and Hubble Frontier Fields. Additionally, we have reconstructed the Spitzer Infrared Array Camera 3.6 and 4.5 \ensuremathμm mosaics, by utilizing all the available archival IPAC Infrared Science Archive/Spitzer Heritage Archive exposures. To alleviate the effect of blending in such a crowded region, we have modeled the Spitzer photometry by convolving the HST detection image with the Spitzer point-spread function using the novel GOLFIR software. The final catalogs contain 218,000 sources, covering a combined area of 690 arcmin^2, a factor of \raisebox-0.5ex\textasciitilde2 improvement over the currently existing photometry. A large number of detected sources is a result of reprocessing of all available and sometimes deeper exposures, in conjunction with a combined optical-near-IR detection strategy. These data will serve as an important tool in aiding the search of the submillimeter galaxies in future ALMA surveys, as well as follow-ups of the HST dark and high-z sources with JWST. Coupled with the available HST photometry, the addition of the 3.6 and 4.5 \ensuremathμm bands will allow us to place a better constraint on the photometric redshifts and stellar masses of these objects, thus giving us an opportunity to identify high-redshift candidates for spectroscopic follow-ups and to answer the important questions regarding the Epoch of Reionization and formation of the first galaxies. The mosaics, photometric catalogs, and the best-fit physical properties are publicly available at https://github.com/dawn-cph/alcs-clusters.

20. arXiv

    Schrodinger’s Galaxy Candidate: Puzzlingly Luminous at z\approx17, or Dusty/Quenched at z\approx5?

    Rohan P. Naidu, Pascal A. Oesch, David J. Setton, Jorryt Matthee, Charlie Conroy, and 20 more authors

    arXiv, Aug 2022

    Abs DOI

    JWST’s first glimpse of the z>10 Universe has yielded a surprising abundance of luminous galaxy candidates. Here we present the most extreme of these systems: CEERS-1749. Based on 0.6-5\mum photometry, this strikingly luminous (\approx26 mag) galaxy appears to lie at z\approx17. This would make it an M_\rmUV≈-22, M_\rm⋆\approx5\times10^9M_\rm⊙ system that formed a mere \sim220 Myrs after the Big Bang. The implied number density of this galaxy and its analogues challenges virtually every early galaxy evolution model that assumes \LambdaCDM cosmology. However, there is strong environmental evidence supporting a secondary redshift solution of z\approx5: all three of the galaxy’s nearest neighbors at <2.5” have photometric redshifts of z\approx5. Further, we show that CEERS-1749 may lie in a z\approx5 protocluster that is rsim5\times overdense compared to the field. Intense line emission at z\approx5 from a quiescent galaxy harboring ionized gas, or from a dusty starburst, may provide satisfactory explanations for CEERS-1749’s photometry. The emission lines at z\approx5 conspire to boost the >2\mum photometry, producing an apparent blue slope as well as a strong break in the SED. Such a perfectly disguised contaminant is possible only in a narrow redshift window (∆z\lesssim0.1), implying that the permitted volume for such interlopers may not be a major concern for z>10 searches, particularly when medium-bands are deployed. If CEERS-1749 is confirmed to lie at z\approx5, it will be the highest-redshift quiescent galaxy, or one of the lowest mass dusty galaxies of the early Universe detected to- date. Both redshift solutions of this intriguing galaxy hold the potential to challenge existing models of early galaxy evolution, making spectroscopic follow-up of this source critical.

21. MNRAS

    

    Dust and the intrinsic spectral index of quasar variations: hints of finite stress at the innermost stable circular orbit

    John R. Weaver and Keith Horne

    Monthly Notices of the Royal Astronomical Society, May 2022

    Abs DOI

    We present a study of 9 242 spectroscopically confirmed quasars with multiepoch ugriz photometry from the SDSS Southern Survey. By fitting a separable linear model to each quasar’s spectral variations, we decompose their five-band spectral energy distributions into variable (disc) and non-variable (host galaxy) components. In modelling the disc spectra, we include attenuation by dust on the line of sight through the host galaxy to its nucleus. We consider five commonly used attenuation laws, and find that the best description is by dust similar to that of the Small Magellanic Cloud, inferring a lack of carbonaceous grains from the relatively weak 2175-Å absorption feature. We go on to construct a composite spectrum for the quasar variations spanning 700-8000 Å. By varying the assumed power-law L_\ensuremathν \ensuremath∝ \ensuremathν^\ensuremathα spectral slope, we find a best-fitting value \ensuremathα = 0.71 \ensuremath\pm 0.02, excluding at high confidence the canonical L_\ensuremathν \ensuremath∝ \ensuremathν^1/3 prediction for a steady-state accretion disc with a T \ensuremath∝ r^-3/4 temperature profile. The bluer spectral index of the observed quasar variations instead supports the model of Agol & Krolik, and Mummery & Balbus, in which a steeper temperature profile, T \ensuremath∝ r^-7/8, develops as a result of finite magnetically induced stress at the innermost stable circular orbit extracting energy and angular momentum from the black hole spin.

22. MNRAS

    

    Pilot-WINGS: An extended MUSE view of the structure of Abell 370

    David J. Lagattuta, Johan Richard, Franz Erik Bauer, Catherine Cerny, Adélaı̈de Claeyssens, and 20 more authors

    Monthly Notices of the Royal Astronomical Society, Jul 2022

    Abs DOI

    We investigate the strong-lensing cluster Abell 370 (A370) using a wide Integral Field Unit (IFU) spectroscopic mosaic from the Multi- Unit Spectroscopic Explorer (MUSE). IFU spectroscopy provides significant insight into the structure and mass content of galaxy clusters, yet IFU-based cluster studies focus almost exclusively on the central Einstein-radius region. Covering over 14 arcmin^2, the new MUSE mosaic extends significantly beyond the A370 Einstein radius, providing, for the first time, a detailed look at the cluster outskirts. Combining these data with wide-field, multi-band Hubble Space Telescope (HST) imaging from the BUFFALO project, we analyse the distribution of objects within the cluster and along the line of sight. Identifying 416 cluster galaxies, we use kinematics to trace the radial mass profile of the halo, providing a mass estimate independent from the lens model. We also measure radially averaged properties of the cluster members, tracking their evolution as a function of infall. Thanks to the high spatial resolution of our data, we identify six cluster members acting as galaxy-galaxy lenses, which constrain localized mass distributions beyond the Einstein radius. Finally, taking advantage of MUSE’s 3D capabilities, we detect and analyse multiple spatially extended overdensities outside of the cluster that influence lensing-derived halo mass estimates. We stress that much of this work is only possible thanks to the robust, extended IFU coverage, highlighting its importance even in less optically dense cluster regions. Overall, this work showcases the power of combining HST + MUSE, and serves as the initial step towards a larger and wider program targeting several clusters.

2021

1. ApJ

   

   The Evolving Interstellar Medium of Star-forming Galaxies, as Traced by Stardust

   Vasily I. Kokorev, Georgios E. Magdis, Iary Davidzon, Gabriel Brammer, Francesco Valentino, and 11 more authors

   The Astrophysical Journal, Nov 2021

   Abs DOI

   We analyze the far-infrared (FIR) properties of \raisebox-0.5ex\textasciitilde5000 star-forming galaxies at z < 4.5, drawn from the deepest, super-deblended catalogs in the GOODS-N and COSMOS fields. We develop a novel panchromatic spectral energy distribution fitting algorithm, Stardust, that models the emission from stars, active galactic nuclei (AGNs), and infrared dust emission, without relying on energy balance assumptions. Our code provides robust estimates of the UV- optical and FIR physical parameters, such as the stellar mass (M_*), dust mass (M_dust), infrared luminosities (L_IR) arising from AGN and star formation activity, and the average intensity of the interstellar radiation field (⟨U⟩). Through a set of simulations we quantify the completeness of our data in terms of M_dust, L_IR, and ⟨U⟩ and subsequently characterize the distribution and evolution of these parameters with redshift. We focus on the dust-to-stellar mass ratio (f_dust), which we parameterize as a function of cosmic age, stellar mass, and specific star formation rate. The f_dust is found to increase by a factor of 10 from z = 0 to z = 2 and appears to remain flat at higher z, mirroring the evolution of the gas fraction. We also find a growing fraction of warm to cold dust with increasing distance from the main sequence, indicative of more intense interstellar radiation fields, higher star formation efficiencies, and more compact star-forming regions for starburst galaxies. Finally, we construct the dust mass functions (DMFs) of star-forming galaxies up to z = 1 by transforming the stellar mass function to DMF through the scaling relations derived here. The evolution of f_dust and the recovered DMFs are in good agreement with the theoretical predictions of the Horizon-AGN and IllustrisTNG simulations. * https://github.com/VasilyKokorev/stardust/

2. ApJ

   

   Extensive Lensing Survey of Optical and Near-infrared Dark Objects (El Sonido): HST H-faint Galaxies behind 101 Lensing Clusters

   Fengwu Sun, Eiichi Egami, Pablo G. Pérez-González, Ian Smail, Karina I. Caputi, and 20 more authors

   The Astrophysical Journal, Dec 2021

   Abs DOI

   We present a Spitzer/IRAC survey of H-faint (H _160 \ensuremath≳ 26.4, < 5\ensuremathσ) sources in 101 lensing cluster fields. Across a CANDELS/Wide-like survey area of \raisebox-0.5ex\textasciitilde648 arcmin^2 (effectively \raisebox-0.5ex\textasciitilde221 arcmin^2 in the source plane), we have securely discovered 53 sources in the IRAC Channel-2 band (CH2, 4.5 \ensuremathμm; median CH2 = 22.46 \ensuremath\pm 0.11 AB mag) that lack robust HST/WFC3-IR F160W counterparts. The most remarkable source in our sample, namely ES-009 in the field of Abell 2813, is the brightest H-faint galaxy at 4.5 \ensuremathμm known so far (CH2 = 20.48 \ensuremath\pm 0.03 AB mag). We show that the H-faint sources in our sample are massive (median M _star = 10^10.3\ensuremath\pm0.3 M _\ensuremath⊙), star-forming (median star formation rate =100_-40^+60 M _\ensuremath⊙ yr^-1), and dust-obscured (A _ V = 2.6 \ensuremath\pm 0.3) galaxies around a median photometric redshift of z = 3.9 \ensuremath\pm 0.4. The stellar continua of 14 H-faint galaxies can be resolved in the CH2 band, suggesting a median circularized effective radius (R _e,circ; lensing corrected) of 1.9 \ensuremath\pm 0.2 kpc and <1.5 kpc for the resolved and whole samples, respectively. This is consistent with the sizes of massive unobscured galaxies at z \raisebox-0.5ex~4, indicating that H-faint galaxies represent the dusty tail of the distribution of a wider galaxy population. Comparing with the ALMA dust continuum sizes of similar galaxies reported previously, we conclude that the heavy dust obscuration in H-faint galaxies is related to the compactness of both stellar and dust continua (R _e,circ \raisebox-0.5ex~1 kpc). These H-faint galaxies make up 16_-7^+13 % of the galaxies in the stellar-mass range of 10^10 - 10^11.2 M _\ensuremath⊙ at z = 3 \raisebox-0.5ex~5, contributing to 8_-4^+8 % of the cosmic star formation rate density in this epoch and likely tracing the early phase of massive galaxy formation.

3. ApJ

   

   Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-redshift Obscured Galaxies

   Caitlin M. Casey, Jorge A. Zavala, Sinclaire M. Manning, Manuel Aravena, Matthieu Béthermin, and 22 more authors

   The Astrophysical Journal, Dec 2021

   Abs DOI

   We present the characteristics of 2 mm selected sources from the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey conducted to date, the Mapping Obscuration to Reionization with ALMA (MORA) survey covering 184 arcmin^2 at 2 mm. Twelve of 13 detections above 5\ensuremathσ are attributed to emission from galaxies, 11 of which are dominated by cold dust emission. These sources have a median redshift of ⟨z_2\,\mathrmmm⟩=3.6_-0.3^+0.4 primarily based on optical/near-infrared photometric redshifts with some spectroscopic redshifts, with 77% \ensuremath\pm 11% of sources at z > 3 and 38% \ensuremath\pm 12% of sources at z > 4. This implies that 2 mm selection is an efficient method for identifying the highest- redshift dusty star-forming galaxies (DSFGs). Lower-redshift DSFGs (z < 3) are far more numerous than those at z > 3 yet are likely to drop out at 2 mm. MORA shows that DSFGs with star formation rates in excess of 300 M _\ensuremath⊙ yr^-1 and a relative rarity of \raisebox-0.5ex\textasciitilde10^-5 Mpc^-3 contribute \raisebox-0.5ex\textasciitilde30% to the integrated star formation rate density at 3 < z < 6. The volume density of 2 mm selected DSFGs is consistent with predictions from some cosmological simulations and is similar to the volume density of their hypothesized descendants: massive, quiescent galaxies at z > 2. Analysis of MORA sources’ spectral energy distributions hint at steeper empirically measured dust emissivity indices than reported in typical literature studies, with ⟨β⟩=2.2_-0.4^+0.5 . The MORA survey represents an important step in taking census of obscured star formation in the universe’s first few billion years, but larger area 2 mm surveys are needed to more fully characterize this rare population and push to the detection of the universe’s first dusty galaxies.

2020

1. ApJ

   

   A Method to Distinguish Quiescent and Dusty Star-forming Galaxies with Machine Learning

   Charles L. Steinhardt, John R. Weaver, Jack Maxfield, Iary Davidzon, Andreas L. Faisst, and 3 more authors

   The Astrophysical Journal, Mar 2020

   Abs DOI

   Large photometric surveys provide a rich source of observations of quiescent galaxies, including a surprisingly large population at z > 1. However, identifying large, but clean, samples of quiescent galaxies has proven difficult because of their near- degeneracy with interlopers such as dusty, star-forming galaxies. We describe a new technique for selecting quiescent galaxies based upon t-distributed stochastic neighbor embedding (t-SNE), an unsupervised machine-learning algorithm for dimensionality reduction. This t-SNE selection provides an improvement both over UVJ, removing interlopers that otherwise would pass color selection, and over photometric template fitting, more strongly toward high redshift. Due to the similarity between the colors of high- and low-redshift quiescent galaxies, under our assumptions, t-SNE outperforms template fitting in 63% of trials at redshifts where a large training sample already exists. It also may be able to select quiescent galaxies more efficiently at higher redshifts than the training sample.

2. ApJS

   

   The BUFFALO HST Survey

   Charles L. Steinhardt, Mathilde Jauzac, Ana Acebron, Hakim Atek, Peter Capak, and 90 more authors

   The Astrophysical Journal Supplement Series, Apr 2020

   Abs DOI

   The Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) is a 101 orbit + 101 parallel Cycle 25 Hubble Space Telescope (HST) Treasury program taking data from 2018 to 2020. BUFFALO will expand existing coverage of the Hubble Frontier Fields (HFF) in Wide Field Camera 3/IR F105W, F125W, and F160W and Advanced Camera for Surveys/WFC F606W and F814W around each of the six HFF clusters and flanking fields. This additional area has not been observed by HST but is already covered by deep multiwavelength data sets, including Spitzer and Chandra. As with the original HFF program, BUFFALO is designed to take advantage of gravitational lensing from massive clusters to simultaneously find high-redshift galaxies that would otherwise lie below HST detection limits and model foreground clusters to study the properties of dark matter and galaxy assembly. The expanded area will provide the first opportunity to study both cosmic variance at high redshift and galaxy assembly in the outskirts of the large HFF clusters. Five additional orbits are reserved for transient follow-up. BUFFALO data including mosaics, value-added catalogs, and cluster mass distribution models will be released via MAST on a regular basis as the observations and analysis are completed for the six individual clusters.

3. MNRAS

   Comparison of stellar populations in simulated and real post-starburst galaxies in MaNGA

   Yirui Zheng, Vivienne Wild, Natalia Lahén, Peter H. Johansson, David Law, and 2 more authors

   Monthly Notices of the Royal Astronomical Society, Oct 2020

   Abs DOI

   Recent integral field spectroscopic (IFS) surveys have revealed radial gradients in the optical spectral indices of post-starburst (PSB) galaxies, which can be used to constrain their formation histories. We study the spectral indices of post-processed mock IFS datacubes of binary merger simulations, carefully matched to the properties of the MaNGA IFS survey, with a variety of black hole (BH) feedback models, progenitor galaxies, orbits, and mass ratios. Based on our simulation sample, we find that only major mergers on prograde-prograde or retrograde-prograde orbits in combination with a mechanical BH feedback model can form galaxies with weak enough ongoing star formation, and therefore absent H \ensuremathα emission, to be selected by traditional PSB selection methods. We find strong fluctuations in nebular emission line strengths, even within the PSB phase, suggesting that H \ensuremathα selected PSBs are only a subsample of the underlying population. The global PSB population can be more robustly identified using stellar continuum-based approaches. The difficulty in reproducing the very young PSBs in simulations potentially indicates that new sub-resolution star formation recipes are required to properly model the process of star formation quenching. In our simulations, we find that the starburst peaks at the same time at all radii, but is stronger and more prolonged in the inner regions. This results in a strong time evolution in the radial gradients of the spectral indices that can be used to estimate the age of the starburst without reliance on detailed star formation histories from spectral synthesis models.

2018

1. A&A

   

   History and destiny of an emerging early-type galaxy. New IFU insights on the major-merger remnant NGC 7252

   J. Weaver, B. Husemann, H. Kuntschner, I. Martı́n-Navarro, F. Bournaud, and 5 more authors

   Astronomy & Astrophysics, Jun 2018

   Abs DOI

   Context. The merging of galaxies is one key aspect in our favourite hierarchical \ensuremathΛCDM Universe and is an important channel leading to massive quiescent elliptical galaxies. Understanding this complex transformational process is ongoing. \Aims: We aim to study NGC 7252, which is one of the nearest major-merger galaxy remnants, observed 1 Gyr after the collision of presumably two gas-rich disc galaxies. It is therefore an ideal laboratory to study the processes inherent to the transformation of disc galaxies to ellipticals. \Methods: We obtained wide-field IFU spectroscopy with the VLT-VIMOS integral-field spectrograph covering the central 50“ \texttimes 50” of NGC 7252 to map the stellar and ionised gas kinematics, and the distribution and conditions of the ionised gas, revealing the extent of ongoing star formation and recent star formation history. \Results: Contrary to previous studies, we find the inner gas disc not to be counter-rotating with respect to the stars. In addition, the stellar kinematics appear complex with a clear indication of a prolate-like rotation component which suggests a polar merger configuration. The ongoing star formation rate is 2.2 \ensuremath\pm 0.6 M_\ensuremath⊙ yr^-1 and implies a typical depletion time of 2 Gyr given the molecular gas content. Furthermore, the spatially resolved star formation history suggests a slight radial dependence, moving outwards at later times. We confirm a large AGN-ionised gas cloud previously discovered 5 kpc south of the nucleus, and find a higher ionisation state of the ionised gas at the galaxy centre relative to the surrounding gas disc. Although the higher ionisation towards the centre is potentially degenerate within the central star forming ring, it may be associated with a low- luminosity AGN. \Conclusions: Although NGC 7252 has been classified as post-starburst galaxy at the centre, the elliptical-like major-merger remnant still appears very active. A central kpc-scale gas disc has presumably re-formed quickly within the last 100 Myr after final coalescence. The disc features ongoing star formation, implying Gyr long timescale to reach the red sequence through gas consumption alone. While NGC 7252 is useful to probe the transformation from discs to ellipticals, it is not well-suited to study the transformation from blue to red at this point.

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