Primordial black hole origin for thermal gamma-ray bursts

Abstract

ABSTRACT A binary black hole (BH) astrophysical scenario where a mass-constrained (2.5 × 10−13M⊙) primordial black hole (PBH) undergoes a radial fall on to its heavier component (such as a supermassive black hole, SMBH) is described as an intense gamma-ray emission event. As the relativistic PBH approaches the Schwarschild SMBH event horizon, its Lorentz-boosted Hawking radiation progressively reduces to a near-zero emission cone resulting in a highly collimated thermal beam. Accordingly, our numerically calculated PBH flux density Sν and νSν fluence spectrum show a decreasing Planck-like spectral dependence consistent with the cooling behaviour of thermal-dominant gamma-ray bursts (GRBs). Our results might provide an alternative explanation for thermal GRBs based on PBH origin.