What determines satellite galaxy disruption?

Abstract

In hierarchical structure formation, dark matter haloes that merge with larger haloes can persist as subhaloes. These subhaloes are likely hosts of visible galaxies. While the dense halo environment rapidly strips subhaloes of their dark mass, the compact luminous material can remain intact for some time, making the correspondence of galaxies with severely stripped subhaloes unclear. Many galaxy evolution models assume that satellite galaxies eventually merge with their central galaxy, but this ignores the possibility of satellite tidal disruption. We use a high-resolution N-body simulation of cosmological volume to explore satellite galaxy merging/disruption criteria based on dark matter subhalo dynamics. We explore the impact that satellite merging/disruption has on the halo occupation distribution and radial profile of the remnants. Using abundance matching to assign stellar mass/luminosity to subhaloes, we compare with observed galaxy clustering, satellite fractions, cluster satellite luminosity functions, finding that subhaloes reproduce well these observables. Our results imply that satellite subhaloes corresponding to >0.2 L* galaxies must be well resolved down to 1-3 per cent of their mass at infall to robustly trace the galaxy population. We also explore a simple analytic model based on dynamical friction for satellite galaxy infall, finding good agreement with our subhalo catalogue and observations. © 2010 The Authors. Journal compilation © 2010 RAS.