2025/09/24 by Deger, Sinan, Peiris, Hiranya V., Thorp, Stephen +5
#Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2509.20430
We study star formation over 12 Gyr using pop-cosmos, a generative model trained on 26-band photometry of 420,000 COSMOS2020 galaxies (IRAC Ch.1 <26). The model learns distributions over 16 SPS parameters via score-based diffusion, matching observed colours and magnitudes. We compute the star formation rate density (SFRD) to z=3.5 by directly integrating individual galaxy SFRs. The SFRD peaks at z=1.3±0.1, with peak value 0.08±0.01 M\odot yr-1 Mpc-3. We classify star-forming (SF) and quiescent (Q) galaxies using specific SFR <10-11 yr-1, comparing with NUVrJ colour selection. The sSFR criterion yields up to 20% smaller quiescent fractions across 00.95) during the most recent ∼300 Myr, then sharp decorrelation with earlier star-forming epochs, marking clear quenching transitions. Massive (10<log10(M_*/M\odot)<11) galaxies quench on a time-scale of ∼1 Gyr, with mass assembly concentrated in their first 3.5 Gyr. Finally, AGN activity (infrared luminosity) peaks as massive (∼1010.5 M_\odot) galaxies approach the transition between star-forming and quiescent states, declining sharply once quiescence is established. This provides evidence that AGN feedback operates in a critical regime during the ∼1 Gyr quenching transition.