What determines satellite galaxy disruption?

TL;DR

This study uses high-resolution simulations to investigate how dark matter subhalos hosting satellite galaxies are disrupted or merge, affecting galaxy distribution models and matching observed clustering and satellite properties.

Contribution

It introduces a simulation-based analysis of satellite disruption criteria and compares the effects of merging versus disruption on galaxy distribution and clustering.

Findings

Subhalos can accurately reproduce observed galaxy clustering and satellite fractions.

Resolving subhalos down to 1-3% of their infall mass is crucial for modeling galaxy populations.

A simple dynamical friction model aligns well with simulation results and observations.

Abstract

In hierarchical structure formation, dark matter halos that merge with larger halos can persist as subhalos. These subhalos are likely hosts of visible galaxies. While the dense halo environment rapidly strips subhalos of their dark mass, the compact luminous material can remain intact for some time, making the correspondence of galaxies with severely stripped subhalos 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 subhalos, we compare with observed galaxy clustering, satellite fractions, cluster satellite luminosity functions, finding that subhalos reproduce well these observables on all scales. Our results imply that satellite subhalos corresponding to >0.2L* galaxies must be well-resolved down to 1-3% 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 catalog and observations.