# Simulations of core formation for frequent dark matter self-interactions

## TL;DR

This paper introduces a novel simulation method that models frequent dark matter self-interactions using adapted smoothed particle hydrodynamics, enabling more accurate studies of core formation in dark matter haloes.

## Contribution

The authors develop a new $N$-body simulation framework that captures frequent dark matter self-interactions through derived energy transfer equations and thermal conductivity.

## Key findings

- Simulated isothermal core formation in dark matter haloes.
- Determined core growth rate as a function of self-scattering cross section.
- Studied effects of different smoothing kernels.

## Abstract

We present the first $N$-body simulations that adapt the equations of smoothed particle hydrodynamics to capture the effect of dark matter self-interactions which are too frequent to be resolved explicitly. The relevant energy transfer equations are derived, the appropriate thermal conductivity is determined and the effects of different smoothing kernels are studied. We apply our framework to simulate the formation of isothermal cores in isolated dark matter haloes and determine the core growth rate as a function of the self-scattering cross section. Our approach may be combined with explicit simulations of rare scatterings in order to simulate accurately the effects of arbitrary dark matter self-interactions in future cosmological simulations.