Speaker
Paulo Ferraz
(University of Coimbra)
Description
We show that highly spinning primordial black holes of mass M ∼ 10^12 kg, potentially born in a matter-dominated era after inflation, can produce clouds of pions in their vicinity via the su- perradiant instability, with densities up to that of nuclear matter. We discuss the electromagnetic signatures of this process, via neutral pion decay and charged pion annihilation into photons, com- puting in particular their contribution to the isotropic gamma-ray background. This allows us to place upper bounds on the abundance of such primordial black holes that are comparable to the ones obtained from Hawking evaporation. We also discuss the possibility of directly observing such clouds in high-redshift superclusters.
