Novel density profile for isothermal cores of dark matter halos

TL;DR

This paper introduces a new simple analytic density profile for self-interacting dark matter halos that accurately models isothermal cores, validated by simulations, and useful for studying halo evolution and initial conditions.

Contribution

The paper presents a novel, analytically tractable density profile specifically designed for SIDM halos with isothermal cores, validated against simulations, and applicable across different evolutionary stages.

Findings

The profile accurately fits density and velocity dispersion in SIDM halos.

It performs well from early thermalization to core-collapse phases.

The profile reduces computational needs for simulations.

Abstract

We present a novel analytic density profile for halos in self-interacting dark matter (SIDM) models, which accurately captures the isothermal-core configuration, i.e. where both the density and velocity dispersion profiles exhibit central plateaus in the halo innermost region. Importantly, the profile retains a simple and tractable functional form. We demonstrate analytically how our density profile satisfies the aforementioned conditions, with comparisons to other contemporary functional choices. We further validate the profile using idealized N-body simulations, showing that it provides excellent representations of both the density and velocity dispersion profiles across a broad range of evolutionary stages, from the early thermalization phase to the late core-collapse regime. As a result of its accuracy and simplicity, the proposed profile offers a robust framework for analyzing halo evolution in a variety of SIDM scenarios. It also holds practical utility in reducing simulation needs and in generating initial conditions for simulations targeting the deep core-collapse regime.