Superradiant axion clouds around asteroid-mass primordial black holes

Abstract We analyze the dynamics and observational signatures of axion clouds formed via superradiant instability around primordial black holes, focusing on mass range 10 14 - 18 kg where latter may account for all dark matter. take into leading effects self-interactions, showing that, even though these limit number axions produced within each cloud, a large become free hole's gravitational potential accumulate in intergalactic medium or host galaxy, depending their escape velocity. This means that hole matter lead to sizeable astrophysical population non-relativistic axions, with masses ranging from 0.1 eV 1 MeV, spin. then show if such couple photons contribution galactic extragalactic background flux, mainly X-ray gamma-ray band spectrum, is already beyond current limits parameters are, therefore, excluded. finish by prospects Athena telescope further probe this co-existence holes axions.