The transformation and quenching of simulated gas-rich dwarf satellites within a group environment

Abstract

The underlying mechanisms driving the quenching of dwarf-mass satellite galaxies remain poorly constrained, but recent studies suggest they are particularly inefficient for those satellites with stellar mass 10$^{\rm 9}$ M$_{\odot}$. We investigate the characteristic evolution of these systems with chemodynamical simulations and idealised models of their tidal/hydrodynamic interactions within the 10$^{\rm 13-13.5}$ M$_{\odot}$ group-mass hosts in which they are preferentially quenched. Our fiducial simulations highlight the role played by secular star formation and stellar bars, and demonstrate a transition from a gas-rich to passive, HI-deficient state (i.e. $\Delta$SFR$\le$-1, def$_{\rm HI}$$\ge$0.5) within 6 Gyr of first infall. Furthermore, in the 8-10 Gyr in which these systems have typically been resident within group hosts, the bulge-to-total ratio of an initially bulgeless disc can increase to 0.3$<$B/T$<$0.4, its specific angular momentum $\lambda_{\rm R}$ reduce to $\sim$0.5, and strong bisymmetries formed. Ultimately, this scenario yields satellites resembling dwarf S0s, a result that holds for a variety of infall inclinations/harassments albeit with broad scatter. The key assumptions here lie in the rapid removal of the satellite's gaseous halo upon virial infall, and the satellite's local intra-group medium density being defined by the host's spherically-averaged profile. We demonstrate how quenching can be greatly enhanced if the satellite lies in an overdensity, consistent with recent cosmological-scale simulations but contrasting with observationally-inferred quenching mechanisms/timescales; an appraisal of these results with respect to the apparent preferential formation of dS0s/S0s in groups is also given.