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

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, $f_{\mathrm{P}\mathrm{B}\mathrm{H}}={\rho }_{\mathrm{P}\mathrm{B}\mathrm{H}}\mathrm{/}{\rho }_{\mathrm{D}\mathrm{M}}$ is obtained for $4\lesssim M_{\mathrm{P}\mathrm{B}\mathrm{H}}\mathrm{/}{M}_{\odot }\lesssim {10}^2$, where ${\rho }_{\mathrm{P}\mathrm{B}\mathrm{H}}$, ${\rho }_{\mathrm{D}\mathrm{M}}$, represent the energy densities of PBHs and DM, respectively, and $M_{\mathrm{P}\mathrm{B}\mathrm{H}}$, 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.