Interstellar medium gas heating by primordial black holes and dark matter particles

TL;DR

This study examines how primordial black holes and dark matter particles jointly heat the interstellar medium in Leo T, deriving constraints on PBH abundance and highlighting the complexities when other particles are involved.

Contribution

It introduces a combined analysis of PBHs and dark matter particles in gas heating, providing new constraints on PBH fractions and exploring the impact of additional particles.

Findings

Stringent constraints on PBH fraction for certain mass ranges when both PBHs and dark photons heat the gas.

Difficulty in constraining PBH abundance when millicharged particles are also involved due to small charge parameters.

Joint heating effects can significantly influence the interpretation of interstellar medium observations.

Abstract

The Leo T dwarf galaxy has been utilized to investigate the heating of interstellar medium gas by both primordial black holes (PBHs) and dark matter (DM) particles. Previous studies have typically assumed that either PBHs or DM particles are responsible for heating the interstellar medium gas. In contrast, this study considers the simultaneous contribution of both PBHs and DM particles to the heating process. If both PBHs and dark photons heat the gas in Leo T, a stringent constraint on the PBH fraction, $f_{\rm PBH}=\rho_{\rm PBH}/\rho_{\rm DM}$ is obtained for $4 \lesssim M_{\rm PBH}/M_\odot \lesssim 10^2$, where $\rho_{\rm PBH}$, $\rho_{\rm DM}$, represent the energy densities of PBHs and DM, respectively, and $M_{\rm PBH}$, and $M_\odot$ denote the masses of PBHs and Sun, respectively. Conversely, if both PBHs and millicharged particles heat the gas, it becomes challenging to impose a more significant constraint on the PBH fraction than previously achieved, due to the very small allowed values of charge parameters within the model.