COSMOS Spectroscopic Redshift Compilation (First Data Release)

Authors

• Ali Ahmad Khostovan, University of KentuckyFollow
• Jeyhan S. Kartaltepe, Rochester Institute of Technology
• Mara Salvato, Max Planck Institute for Extraterrestrial Physics
• Olivier Ilbert, Laboratoire d'Astrophysique de Marseille
• Caitlin M. Casey, University of California at Santa Barbara
• Hiddo Algera, Academia Sinica - Institute of Astronomy and Astrophysics
• Jacqueline Antwi-Danso, University of Toronto
• Andrew Battisti, University of Western Australia
• Malte Brinch, Universidad de Valparaíso
• Marcella Brusa, University of Bologna
• Antonello Calabrò, Osservatorio Astronomico Roma
• Peter L. Capak, Cosmic Dawn Center
• Nima Chartab, California Institute of Technology
• Olivia R. Cooper, University of Texas at Austin
• Isa G. Cox, Rochester Institute of Technology
• Behnam Darvish, University of California Riverside
• Nicole E. Drakos, University of Hawaii at Hilo
• Andreas L. Faisst, California Institute of Technology
• Matthew R. George, University of California Berkeley
• Ghassem Gozaliasl, Aalto University
• Santosh Harish, Rochester Institute of Technology
• Günther Hasinger, Technische Universität Dresden
• Hossein Hatamnia, University of California Riverside
• Angela Iovino, Osservatorio Astronomico di Brera
• Shuowen Jin, Cosmic Dawn Center
• Daichi Kashino, National Institutes of Natural Sciences, National Astronomical Observatory of Japan
• Anton M. Koekemoer, Space Telescope Science Institute
• Ronaldo Laishram, National Institutes of Natural Sciences, National Astronomical Observatory of Japan
• Khee Gan Lee, University of Tokyo
• Jitrapon Lertprasertpong, Rochester Institute of Technology
• Simon J. Lilly, Swiss Federal Institute of Technology Zurich
• Daizhong Liu, CAS - Purple Mountain Observatory

Abstract

We present the COSMOS Spectroscopic Redshift Compilation encompassing ∼20 yr of spectroscopic redshifts within a 10 deg² area centered on the 2 deg² 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 ∼10^8.4-10¹⁰ 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.

Document Type

Article

Publication Date

1-1-2026

Notes/Citation Information

Publisher Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Digital Object Identifier (DOI)

10.3847/1538-4365/ae1cb9

Archival?

Archival

Repository Citation

Khostovan, Ali Ahmad; Kartaltepe, Jeyhan S.; Salvato, Mara; Ilbert, Olivier; Casey, Caitlin M.; Algera, Hiddo; Antwi-Danso, Jacqueline; Battisti, Andrew; Brinch, Malte; Brusa, Marcella; Calabrò, Antonello; Capak, Peter L.; Chartab, Nima; Cooper, Olivia R.; Cox, Isa G.; Darvish, Behnam; Drakos, Nicole E.; Faisst, Andreas L.; George, Matthew R.; Gozaliasl, Ghassem; Harish, Santosh; Hasinger, Günther; Hatamnia, Hossein; Iovino, Angela; Jin, Shuowen; Kashino, Daichi; Koekemoer, Anton M.; Laishram, Ronaldo; Lee, Khee Gan; Lertprasertpong, Jitrapon; Lilly, Simon J.; and Liu, Daizhong, "COSMOS Spectroscopic Redshift Compilation (First Data Release)" (2026). Physics and Astronomy Faculty Publications. 792.
https://uknowledge.uky.edu/physastron_facpub/792