Star Formation and Quenching of Satellite Galaxies

Abstract

We study the quenching of satellite galaxies by gradual depletion of gas due to star formation, by ram-pressure striping and by tidally triggered starburst. Using progenitors constrained by the empirical model of Lu et al., in which outflow loading factor is low, we do not find an over-quenching problem in satellites even if there is no further cold gas supply from the cooling of the halo gas after a galaxy is accreted by its host. Gradual depletion alone predicts a unimodal distribution in specific star formation, in contrast to the bimodal distribution observed, and under-predicts the quenched fraction in low mass halos. Ram-pressure stripping nicely reproduces the bimodal distribution but under-predicts the quenched fraction in low-mass halos. Starbursts in gas-rich satellites triggered by tidal interactions with central galaxies can nicely reproduce the quenched satellite population in low-mass halos, but become unimportant for low-mass satellites in massive halos. The combined processes, together with the constrained progenitors, can reproduce the observed star formation properties of satellites in halos of different masses.