Beasts in the Bubbles: Remarkably UV-bright Galaxies at z=9-10

Keck/MOSFIRE | 2N | PI - C. Casey

We propose Keck MOSFIRE J-band spectroscopy for four UV-bright (H=24.5–25.4 mag) novel photometric candidates at z=9-10 from the new COSMOS2020 catalogs, with deeper, homogeneous near-IR and ultra-deep optical coverage that allowed for the identification of such rare, extraordinary candidates. All candidates have (a) clear Lyman-break features from Y to H bands, (b) IRAC detection, (c) tight distributions in PDF(z) at z=9-10, (d) inconsistency with common high-z galaxy contaminants (low-mass stars and dusty lower-z galaxies), and (e) are estimated to sit at z>9 with four independent fits to their photometry. The volume density of these four candidates is also consistent with the bright-end of the latest UV luminosity function (UVLF) studies at z=9-10. With the proposed observations, we will achieve the following three major goals: 1) redshift confirmation and thus the power-law nature of the UVLF at z=9-10; 2) testing if UV-bright galaxies at z=9-10 reside in ionized bubbles; and 3) if they host AGN measured via the Nv1243 line. Importantly, our targets are > 10-20 times brighter than the only other source confirmed with line emission at these redshifts. The spectroscopic confirmation of our targets will provide essential constraints on the bright/massive-end of luminosity/mass function at z>9 and the cold dark matter formation of early, massive galaxies.

John R. Weaver
John R. Weaver
Postdoctoral Research Associate

My research interests lie almost exclusively within the realm of extragalactic astrophysics and cosmology. I use state-of-the-art optical and infrared observatories and surveys to study the lives of galaxies, and how their properties change over cosmic time. This includes detailed case studies of individual galaxies, as well as statistical analyses of large survey catalogs.