Collisional interaction limits between dark matters and baryons in `cooling flow' clusters

TL;DR

This study constrains the interaction cross section between dark matter particles and protons in galaxy clusters, suggesting such collisions are unlikely to significantly heat the intracluster medium and are limited in their effectiveness.

Contribution

It provides new upper limits on dark matter-proton cross sections in galaxy clusters using X-ray data and analyzes the stability of DMP-baryon interactions as a heating mechanism.

Findings

Upper limit on cross section: σ₀/mₓ ≲ 2×10⁻²⁵ cm² GeV⁻¹

DMP-baryon collisions unlikely to be a stable heating source

Collisional interactions are constrained and not dominant in cluster cores

Abstract

Presuming weak collisional interactions to exchange the kinetic energy between dark matter and baryonic matter in a galaxy cluster, we re-examine the effectiveness of this process in several `cooling flow' galaxy clusters using available X-ray observations and infer an upper limit on the heavy dark matter particle (DMP)$-$proton cross section $\sigma_{\rm xp}$. With a relative collisional velocity $V-$dependent power-law form of $\sigma_{\rm xp}=\sigma_0(V/10^3 {\rm km s^{-1}})^a$ where $a\leq 0$, our inferred upper limit is $\sigma_0/m_{\rm x}\lsim 2\times10^{-25} {\rm cm}^2 {\rm GeV}^{-1}$ with $m_{\rm x}$ being the DMP mass. Based on a simple stability analysis of the thermal energy balance equation, we argue that the mechanism of DMP$-$baryon collisional interactions is unlikely to be a stable nongravitational heating source of intracluster medium (ICM) in inner core regions of `cooling flow' galaxy clusters.