COSMOS Spectroscopic Redshift Compilation (First Data Release): 488,000 Redshifts Encompassing Two Decades of Spectroscopy
Ali Ahmad Khostovan, Jeyhan S. Kartaltepe, M. Salvato, O. Ilbert, Caitlin M. Casey, Hiddo Algera, Jacqueline Antwi-Danso, Andrew Battisti, Malte Brinch, M. Brusa, Antonello Calabrò, P. Capak, Nima Chartab, Olivia R. Cooper, Isabella G. Cox, Behnam Darvish, Nicole E. Drakos, Andreas L. Faisst, Matthew R. George, G. Gozaliasl, Santosh Harish, G. Hasinger, Hossein Hatamnia, A. Iovino, Shuowen Jin, Daichi Kashino, Anton M. Koekemoer, Ronaldo Laishram, Khee‐Gan Lee, Jitrapon Lertprasertpong, S. J. Lilly, Daizhong Liu, Daniel Masters, Bahram Mobasher, Tohru Nagao, Masato Onodera, Yingjie Peng, D. B. Sanders, Ryan L. Sanders, Zahra Sattari, N. Z. Scoville, Ekta A. Shah, J. D. Silverman, N. Suzuki, Sina Taamoli, Masayuki Tanaka, L. Tasca, Sune Toft, Greta Toni, Benny Trakhtenbrot, Jonathan R. Trump, M. Vaccari, Francesco Valentino, Brittany N. Vanderhoof, John R. Weaver, Min S. Yun, Jorge A. Zavala
Abstract
Abstract We present the COSMOS Spectroscopic Redshift Compilation encompassing ∼20 yr of spectroscopic redshifts within a 10 deg 2 area centered on the 2 deg 2 COSMOS legacy field. This compilation contains 487,666 redshifts of 266,284 unique objects from 138 individual programs up to z ∼ 8 with median stellar mass ∼10 8.4 –10 10 M ⊙ (redshift dependent). Rest-frame NUVrJ colors and star formation rate–stellar mass correlations show that 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 ∼ 23.4 mag and K s ∼ 21.6 mag; however, this is redshift dependent. Spatially, the compilation is >50% (>30%) complete within the central (outer) region 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 subpopulations currently lacking spectroscopic coverage, including z < 1 intermediate-mass quiescent and low-/intermediate-mass bursty star-forming galaxies, z ∼ 2 massive quiescent galaxies, and z > 3 massive star-forming galaxies. This 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 incorporating new spectroscopic redshifts and providing a lasting legacy resource for the community.