Constraining Dissipative Dark Matter Self-Interactions

TL;DR

This paper investigates how dissipative self-interactions in dark matter can accelerate halo core collapse, affecting density profiles and providing constraints based on dwarf galaxy observations.

Contribution

It introduces a semianalytical model for gravothermal evolution with dissipative interactions, calibrated with simulations, and derives observational constraints.

Findings

Dissipative interactions accelerate core collapse in dark matter halos.

Inner density profiles can become cuspy again at late times.

Constraints on interaction strength are derived from dwarf galaxy data.

Abstract

We study the gravothermal evolution of dark matter halos in the presence of dissipative dark matter self-interactions. Dissipative interactions are present in many particle-physics realizations of the dark-sector paradigm and can significantly accelerate the gravothermal collapse of halos compared to purely elastic dark matter self-interactions. This is the case even when the dissipative interaction timescale is longer than the free-fall time of the halo. Using a semianalytical fluid model calibrated with isolated and cosmological $N$-body simulations, we calculate the evolution of the halo properties -- including its density profile and velocity dispersion profile -- as well as the core-collapse time as a function of the particle model parameters that describe the interactions. A key property is that the inner density profile at late times becomes cuspy again. Using 18 dwarf galaxies that exhibit a corelike dark matter density profile, we derive constraints on the strength of the dissipative interactions and the energy loss per collision.