A Baryonic Solution to the Missing Satellites Problem

TL;DR

This paper demonstrates that incorporating baryonic physics into simulations significantly reduces the predicted number of luminous satellite galaxies around Milky Way-like galaxies, aligning theoretical predictions with observations and addressing the missing satellites problem.

Contribution

The study applies a baryonic correction to dark matter-only simulations, showing it can resolve the discrepancy in satellite galaxy counts around Milky Way-mass galaxies.

Findings

Baryonic physics reduces the number of massive subhalos in simulations.

Corrected simulations match observed satellite counts around the Milky Way.

Baryonic processes can potentially solve the missing satellites problem.

Abstract

It has been demonstrated that the inclusion of baryonic physics can alter the dark matter densities in the centers of low-mass galaxies, making the central dark matter slope more shallow than predicted in pure cold dark matter simulations. This flattening of the dark matter profile can occur in the most luminous subhalos around Milky Way-mass galaxies. Zolotov et al. (2012) have suggested a correction to be applied to the central masses of dark matter-only satellites in order to mimic the affect of (1) the flattening of the dark matter cusp due to supernova feedback in luminous satellites, and (2) enhanced tidal stripping due to the presence of a baryonic disk. In this paper, we apply this correction to the z=0 subhalo masses from the high resolution, dark matter-only Via Lactea II (VL2) simulation, and find that the number of massive subhalos is dramatically reduced. After adopting a stellar mass to halo mass relationship for the VL2 halos, and identifying subhalos that are (1) likely to be destroyed by stripping and (2) likely to have star formation suppressed by photo-heating, we find that the number of massive, luminous satellites around a Milky Way-mass galaxy is in agreement with the number of observed satellites around the Milky Way or M31. We conclude that baryonic processes have the potential to solve the missing satellites problem.