Authors:
(1) Antonio Riotto, Département de Physique Theorique, Universite de Geneve, 24 quai Ansermet, CH-1211 Geneve 4, Switzerland and Gravitational Wave Science Center (GWSC), Universite de Geneve, CH-1211 Geneva, Switzerland;
(2) Joe Silk, Institut d’Astrophysique, UMR 7095 CNRS, Sorbonne Universite, 98bis Bd Arago, 75014 Paris, France, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore MD 21218, USA, and Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH, UK.
Table of Links
2.1 What is the abundance of PBHs?
2.2 What is the effect of PBH clustering?
2.3 What fraction of the currently observed GW events can be ascribed to PBHs?
3.3 Plugging the pair instability gap with PBH?
3.4 PBH eccentricity, 3.5 PBH spin and 3.6 Future gamma-ray telescopes
3.6 Future gamma-ray telescopes
PBHs have a range of potentially interesting direct gamma ray signals associated with Hawking evaporation. These include the 511 keV gamma-ray line, produced by electron-positron pair-annihilation, where positrons originate from black hole evaporation. The INTEGRAL detection of the Large Magellanic Cloud provides one of the strongest bounds attainable with present observations, and should be greatly improved upon by future MeV gamma-ray telescopes such as GECCO [60], as well as AMEGO [61] and ASTROGRAM [62], among others [63].
Exploding PBHs, the late-time limit of Hawking evaporation for small PBHs, provide intriguing candidates for future very high energy gamma ray telescopes that may address transient phenomena, that pertain especially to the new frontier of PBHs of ultralralow masses.
![Figure 3: Flowchart from Ref. [47] to assess the primordial nature of a binary merger based on measurements of the redshift z, eccentricity e, tidal deformability Λ, component masses m, and dimensionless spins χ. Each arrow indicates if the condition in the box is met (green) or violated (red).](https://cdn.hackernoon.com/images/fWZa4tUiBGemnqQfBGgCPf9594N2-w5830nu.png)
Such gamma ray experiments include HAWC (100 GeV -50 TeV) and CTA (20 GeV-300 TeV) [66] at TeV scales, and at PeV-scale photon energies LHAASO [67] and SWGO [68]. Such searches will be closely coordinated with multimessenger projects spanning next generation underground gravitational wave telescopes (EINSTEIN (ET), COSMIC EXPLORER (CE)) and FRB observatories (CHORD) [69].
This paper is available on arxiv under CC BY 4.0 DEED license.