COSMOS2020: a stepping stone for the next generation of galaxy surveys

COSMOS is one of the most valuable fields of observation for extragalactic science, due in part to continued investment in multi-chromatic observation. It is then no surprise that it has played a pivotal role in our understanding of galaxy evolution, especially at early times where sources are too faint to be studied en masse by comparably shallow, wide-field surveys. Now in the decade of groundbreaking optical-NIR facilities such as the Nancy Roman Space Telescope, alongside JWST, LSST, and Euclid, the stage is set to probe deeper into the Universe than ever before. COSMOS is the natural stepping stone in this progressively deeper investigation and has been selected as one of the primary calibration fields for forthcoming surveys. It is for these reasons why we must continue to innovate. We present COSMOS2020, the latest installment of catalogs to map COSMOS, now at unprecedented optical-NIR depths in excess of 28 mags over 2 deg2. A total of 37 bands of photometry are newly extracted for 1M sources using bleeding-edge profile-fitting photometry provided by The Tractor. We find intensely competitive measurements compared to an identical extraction with SExtractor, benchmarked by photometric redshift accuracy below 2% at i < 24. Incredibly, we show that The Tractor provides the incredibly robust high-redshift photometry with remarkably little photometric redshift bias, underscoring the transformative role of profile-fitting photometry in the next generation of galaxy surveys.

John R. Weaver
John R. Weaver
PhD Fellow in Astrophysics

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.