Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope

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Author/Creator ORCID

Date

2018-04-11

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Citation of Original Publication

M. Ackermann et al, Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope, The Astrophysical Journal, Volume 857, Number 1,2018, doi: https://doi.org/10.3847%2F1538-4357%2Faaac7b

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law

Subjects

Abstract

Black holes with masses below approximately 10¹⁵ g are expected to emit gamma-rays with energies above a few tens of MeV, which can be detected by the Fermi Large Area Telescope (LAT). Although black holes with these masses cannot be formed as a result of stellar evolution, they may have formed in the early universe and are therefore called primordial black holes (PBHs). Previous searches for PBHs have focused on either short-timescale bursts or the contribution of PBHs to the isotropic gamma-ray emission. We show that, in cases of individual PBHs, the Fermi-LAT is most sensitive to PBHs with temperatures above approximately 16 GeV and masses 6 × 10¹¹ g, which it can detect out to a distance of about 0.03 pc. These PBHs have a remaining lifetime of months to years at the start of the Fermi mission. They would appear as potentially moving point sources with gamma-ray emission that become spectrally harder and brighter with time until the PBH completely evaporates. In this paper, we develop a new algorithm to detect the proper motion of gamma-ray point sources, and apply it to 318 unassociated point sources at a high galactic latitude in the third Fermi-LAT source catalog. None of the unassociated point sources with spectra consistent with PBH evaporation show significant proper motion. Using the nondetection of PBH candidates, we derive a 99% confidence limit on the PBH evaporation rate in the vicinity of Earth, ⍴PBH < 7.2 x 10³ pc⁻³ yr⁻¹. This limit is similar to the limits obtained with ground-based gamma-ray observatories.