2025/04/02 by Lim, Seunghwan, Tacchella, Sandro, Maiolino, Roberto +2
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2504.02027
Exploiting a large sample of 5.3 million galaxies with M_∗ = 1010-11 \rm M_\odot from the highest-resolution FLAMINGO simulation, we carry out a statistical analysis of quiescent and star-forming galaxies to explore quenching mechanisms. From redshift z ≃ 7 to 0, we find that the median star-formation rate of main-sequence galaxies is independent of the environment and of whether a galaxy is a central or satellite, whereas the fraction of quiescent galaxies is highly sensitive to both. By employing Random Forest (RF) classifiers, we demonstrate that black hole (BH) feedback is the most responsible quenching mechanism for both centrals and satellites, while halo mass is the second most significant. For satellites, a notable importance given by RF to stellar mass implies in-situ pre-quenching rather than ex-situ preprocessing prior to infall to the current host halo. In the cosmic afternoon of z = 0 -- 1, we identify two distinct regimes of evolution: at M\rm BH \gtrsim 107 \rm M_\odot, essentially all galaxies are quenched regardless of their environment; at M\rm BH \lesssim 107 \rm M_\odot, quenching is determined mainly by halo mass. Galaxies undergo a sharp transition from the main sequence to quiescence once their BH mass reaches M\rm BH ≃ 107 \rm M_\odot (typically when M_∗ ≃ 1010.5 \rm M_\odot and M\rm h ≃ 1012 \rm M_\odot) with a short quenching timescale of < 1 Gyr. This transition is driven by a sudden change in the gas mass in the inner circum-galactic medium. Our results indicate that galaxy quenching arises from a combination of in-situ and ex-situ physical processes.