How Does Feedback Affect Milky Way Satellite Formation?

TL;DR

This study uses high-resolution hydrodynamic simulations to explore how supernova feedback and reionisation influence the formation and survival of Milky Way satellite galaxies, revealing that feedback reduces stellar mass but not satellite count.

Contribution

It provides new insights into the timing and effects of feedback processes on the formation of MW satellites using detailed high-redshift simulations.

Findings

Low-mass satellites form mostly before redshift 8.

Supernova feedback reduces stellar mass but not satellite numbers.

Survival depends on accretion timing relative to redshift 3.

Abstract

We use sub-parsec resolution hydrodynamic resimulations of a Milky Way (MW) like galaxy at high redshift to investigate the formation of the MW satellite galaxies. More specifically, we assess the impact of supernova feedback on the dwarf progenitors of these satellite, and the efficiency of a simple instantaneous reionisation scenario in suppressing star formation at the low-mass end of this dwarf distribution. Identifying galaxies in our high redshift simulation and tracking them to z=0 using a dark matter halo merger tree, we compare our results to present-day observations and determine the epoch at which we deem satellite galaxy formation must be completed. We find that only the low-mass end of the population of luminous subhalos of the Milky-Way like galaxy is not complete before redshift 8, and that although supernovae feedback reduces the stellar mass of the low-mass subhalos (log(M/Msolar) < 9), the number of surviving satellites around the Milky-Way like galaxy at z = 0 is the same in the run with or without supernova feedback. If a luminous halo is able to avoid accretion by the Milky-Way progenitor before redshift 3, then it is likely to survive as a MW satellite to redshift 0.