Ram pressure stripping of halo gas in disk galaxies: Implications on galactic star formation in different environments
Abstract
We numerically investigate evolution of gaseous halos around disk galaxies in different environments ranging from small groups to rich clusters in order to understand galaxy evolution in these environments. Our simulations self-consistently incorporate effects of ram pressure of intergalactic medium (IGM) on disk and halo gas of galaxies and hydrodynamical interaction between disk and halo gas so that mass fractions of halos gas stripped by ram pressure of IGM (Fstrip) can be better estimated. We mainly investigate how Fstrip depends on total masses of their host environments (Mhost), galactic masses (Mgal), densities and temperature of IGM (TIGM and rhoIGM, respectively), relative velocities between IGM and galaxies (Vr), and physical properties of disks (e.g., gas mass fraction). We find that typically 60-80% of halo gas can be efficiently stripped from Milky Way-type disk galaxies by ram pressure in clusters with Mhost 1014 Msun We also find that Fstrip depends on Mhost such that Fstrip is higher for larger Mhost. Furthermore it is found that Fstrip can be higher in disk galaxies with smaller Mgal for a given environment. Our simulations demonstrate that the presence of disk gas can suppress ram pressure stripping of halo gas owing to hydrodynamical interaction between halo and disk gas. Ram pressure stripping of halo gas is found to be efficient (i.e., Fstrip>0.5) even in small and/or compact groups, if rhoIGM ~ 105 Msun/kpc3 and Vr ~ 400 km/s. Based on the derived radial distributions of remaining halo gas after ram pressure stripping, we propose that truncation of star formation after halo gas stripping can occur outside-in in disk galaxies.