Limits on primordial black holes from the extragalactic gamma-ray background; current status and future projections
ORAL
Abstract
Primordial black holes (PBHs) of mass of the order 1015 grams, have an evaporation lifetime via Hawking radiation similar to the age of the universe and can contribute to the observed gamma-ray fluxes at the MeV and GeV range. In this talk, I will show limits on the abundance of PBHs with masses in the range of 1014 to 1017 grams. Such limits come from the observed isotropic gamma-ray background (IGRB), measured by Fermi-LAT, EGRET, COMPTEL and the SMM telescope that cover gamma-ray energies from 1 MeV to 1 TeV.
The IGRB is the result of several classes of extragalactic astrophysical sources. Those sources include blazars, start-forming galaxies and radio galaxies. Also, ultra-high-energy cosmic rays interacting with the infrared background, contribute to the isotropic background. Using information from \textit{Fermi}'s gamma-ray sources catalog and the results of dedicated studies of these classes of sources, from observations at the infrared and radio, I will show how to model their contribution to the IGRB. Moreover, I will show how we model the gamma-ray spectrum form the evaporation of PBHs. We include the direct Hawking radiation of gamma rays, gamma rays produced in the hadronization and decay of unstable particles as well as final state radiation gamma rays and gamma rays from positrons produced by the PBHs that then pair annihilate with interstellar medium electrons. Finally, I will discuss how future observations from AMEGO-X and e-ASTROGAM will affect the constraints on the abundance of PBHs.
The IGRB is the result of several classes of extragalactic astrophysical sources. Those sources include blazars, start-forming galaxies and radio galaxies. Also, ultra-high-energy cosmic rays interacting with the infrared background, contribute to the isotropic background. Using information from \textit{Fermi}'s gamma-ray sources catalog and the results of dedicated studies of these classes of sources, from observations at the infrared and radio, I will show how to model their contribution to the IGRB. Moreover, I will show how we model the gamma-ray spectrum form the evaporation of PBHs. We include the direct Hawking radiation of gamma rays, gamma rays produced in the hadronization and decay of unstable particles as well as final state radiation gamma rays and gamma rays from positrons produced by the PBHs that then pair annihilate with interstellar medium electrons. Finally, I will discuss how future observations from AMEGO-X and e-ASTROGAM will affect the constraints on the abundance of PBHs.
*This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award No. DE-SC0022352.
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Presenters
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Ilias Cholis
- Oakland University