Gamma-ray emission from primordial black hole-neutron star interaction

Abstract

The interaction of an asteroid-mass primordial black hole (PBH) with a slowly-rotating neutron star (NS) can lead to detectable gamma-ray emission via modern observatories like Fermi-LAT or e-ASTROGRAM. Depending on the specific PBH relativistic orbit in the NS Schwarschild spacetime and the relative orientation of this binary system with respect to Earth, the PBH Hawking radiation will show a characteristic temperature profile over time. Essentially, a moderate heating behaviour (or even a progressive and constant cooling phase) is found for the majority of the event, followed by a sudden and dramatic cool-down at the end of the burst. Our theoretical model might provide a means of identification of such hypothetical PBH-NS interactions, based on the distinctive temperature evolution of thermal-like gamma ray bursts (GRBs) described in this article.