CMB bounds on primordial black holes with dark matter mini-halos: the role of radiative feedback

Abstract

Observations of the cosmic microwave background constrain the abundance of primordial black holes, as these would accrete gas and inject energy into the cosmological medium. We have revisited these constraints, taking into account the local heating and ionisation of the gas around the black holes. While constraints for \textit{naked} black holes are not significantly affected, bounds including dark matter mini-halos are drastically relaxed. This result suggests that previous analysis may have significantly overestimated the role of dark matter mini-halos in boosting the accretion rates.