Primordial black holes and the observed Galactic 511 keV line

Abstract

The observed 511 keV line from the Galactic Bulge is a real challenge for theoretical astrophysics: despite a lot of suggested mechanisms, there is still no convincing explanation and the origin of the annihilated positrons remains unknown. Here we discuss the possibility that a population of slowly evaporating primordial black holes with the mass around $10^{16}-10^{17}$ g ejects (among other particles) low--energy positrons into the Galaxy. In addition to positrons, we have also calculated the spectrum and number density of photons and neutrinos produced by such black holes and found that the photons are potentially observable in the near future, while the neutrino flux is too weak and below the terrestrial and extra--terrestrial backgrounds. Depending on their mass distribution, such black holes could make a small fraction or the whole cosmological dark matter.

7 pages, 7 figures. v4: refereed version + erratum

References in corpus (6)

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• Hawking-like radiation does not require a trapped region
• Constraints on Light Dark Matter From Core-Collapse Supernovae
• Microquasars as sources of positron annihilation radiation
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Cited by in corpus (13)

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• Observational Evidence for Primordial Black Holes: A Positivist Perspective
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• Inhomogeneous baryogenesis, cosmic antimatter, and dark matter
• Near future MeV telescopes can discover asteroid-mass primordial black hole dark matter
• Primordial black hole constraints with Hawking radiation -- a review
• Constraints on amplitudes of curvature perturbations from primordial black holes
• The 511 keV Excess and Primordial Black Holes
• Implications of primordial black holes on the first stars and the origin of the super--massive black holes
• The Sensitivity of Future Gamma-Ray Telescopes to Primordial Black Holes
• Search for primordial black hole dark matter with X-ray spectroscopic and imaging satellite experiments and prospects for future satellite missions
• Cosmic antimatter: models and observational bounds
• The Dark Dimension, the Swampland, and the Dark Matter Fraction Composed of Primordial Black Holes