2025/06/04 by Baker, William M., Valentino, Francesco, Lagos, Claudia del P. +6 · 4 citations
#Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2506.04119
High-redshift (z>2) massive quiescent galaxies are crucial tests of early galaxy formation and evolutionary mechanisms through their cosmic number densities and stellar mass functions (SMFs). We explore a sample of 743 massive (\rm M_*> 109.5M_\odot) quiescent galaxies from z=2-7 in over 800 arcmin2 of NIRCam imaging from a compilation of public JWST fields (with a total area > 5 × previous JWST studies). We compute and report their cosmic number densities, stellar mass functions, and cosmic stellar mass density. We confirm a significant overabundance of massive quiescent galaxies relative to a range of cosmological hydrodynamical simulations and semi-analytic models (SAMs). We find that no simulations or SAMs accurately reproduce the SMF for massive quiescent galaxies at any redshift within the interval z=2-5. This shows that none of these models' feedback prescriptions are fully capturing high-z galaxy quenching, challenging the standard formation scenarios. We find a greater abundance of lower-mass (\rm M_*<1010M_\odot) quiescent galaxies than previously found, highlighting the importance of sSFR cuts rather than simple colour selection. We show the importance of this selection bias, alongside individual field-to-field variations caused by cosmic variance, in varying the observed quiescent galaxy SMF, especially at higher-z. We also find a steeper increase in the cosmic stellar mass density for massive quiescent galaxies than has been seen previously, with ρ_*∝ (1+z)-7.2±0.3, indicating the dramatic increase in the importance of galaxy quenching within these epochs.