Constraining Self-Interacting Dark Matter with Dwarf Spheroidal Galaxies and High-resolution Cosmological $N$-body Simulations

TL;DR

This study uses high-resolution cosmological simulations to compare dark matter models, finding that self-interacting dark matter with a cross-section less than 3 cm²/g better matches dwarf galaxy observations, especially for satellites with small pericenters.

Contribution

It provides new constraints on self-interacting dark matter properties by analyzing subhalo densities and their dependence on orbital parameters in detailed simulations.

Findings

Self-interacting dark matter with  cm8g^{-1} is favored by dwarf galaxy data.

Central densities of subhalos differ notably between models for small pericenter orbits.

Milky-Way satellites with small pericenters are key to further constraining dark matter nature.

Abstract

We study the density structures of dark matter subhalos for both cold dark matter and self-interacting dark matter models using high-resolution cosmological $N$-body simulations. We quantify subhalo's central density at 150 pc from the center of each subhalo at the classical dwarf spheroidal and ultrafaint dwarf scales found in Milky-Way sized halos. By comparing them with observations, we find that the self-interacting scattering cross-section of $\sigma/m<3\ \rm{cm^{2}g^{-1}}$ is favored. Due to the combination of hosts' tide and self-interactions, the central density of subhalos with small pericenter shows a noticeable difference between the cold and the self-interacting models, indicating that Milky-Way satellites with small pericenter are ideal sites to further constrain the nature of dark matter by future large spectroscopic surveys.