Satellite survival in cold dark matter cosmology

TL;DR

This paper investigates the factors influencing the survival of dark matter substructures within larger halos, emphasizing the limited role of tidal forces and clump interactions in their destruction.

Contribution

It introduces a new perspective on substructure survival, challenging the assumption that tidal fields alone can eliminate clumps, and explores alternative mechanisms during virialization.

Findings

Tidal destruction requires spherical symmetry at formation.

Clump-clump encounters are ineffective in homogenizing halos.

Phase mixing accelerates in inner regions, affecting stellar disk evolution.

Abstract

We study the survival of substructures (clumps) within larger self-gravitating dark matter halos. Building on scaling relations obtained from N-body calculations of violent relaxation, we argue that the tidal field of galaxies and halos can only destroy substructures if spherical symmetry is imposed at formation. We explore other mechanisms that may tailor the number of halo substructures during the course of virialization. Unless the larger halo is built up from a few large clumps, we find that clump-clump encounters are unlikely to homogenize the halo on a dynamical timescale. Phase mixing would proceed faster in the inner parts and allow for the secular evolution of a stellar disk.