# Diversity in density profiles of self-interacting dark matter satellite halos

## TL;DR

This study uses N-body simulations to explore how self-interacting dark matter affects the density profiles of satellite halos, revealing diverse core structures that could explain the variety observed in Milky Way dwarf galaxies.

## Contribution

It demonstrates how SIDM leads to a range of core sizes and densities in satellite halos, depending on orbit and cross section, advancing understanding of dark matter behavior in galaxy formation.

## Key findings

- High-concentration subhalos undergo core collapse
- Low-concentration subhalos develop large low-density cores
- Diversity in satellite densities can be explained by SIDM effects

## Abstract

We present results from N-body simulations of self-interacting dark matter (SIDM) subhalos, which could host ultra-faint dwarf spheroidal galaxies, inside a Milky-Way-like main halo. We find that high-concentration subhalos are driven to gravothermal core collapse, while low-concentration subhalos develop large (kpc-sized) low-density cores, with both effects depending sensitively on the satellite's orbit and the self-interaction cross section over mass $\sigma/m$. The overall effect for $\sigma/m \gtrsim 3 \ \rm cm^2/g$ is to increase the range of inner densities, potentially explaining the observed diversity of Milky Way satellites, which include compact systems like Draco and Segue 1 that are dense in dark matter, and less dense, diffuse systems like Sextans and Crater II. We discuss possible ways of distinguishing SIDM models from collisionless dark matter models using the inferred dark matter densities and stellar sizes of the dwarf spheroidal galaxies.