# Constraining primordial black hole abundance with the Galactic 511 keV line

## TL;DR

This paper uses measurements of the Galactic 511 keV line to set new constraints on the abundance of primordial black holes in the mass range of 10^{16} to 10^{17} grams, ruling out their role as the sole dark matter component.

## Contribution

It introduces a novel method of constraining primordial black hole abundance using gamma-ray observations of positron annihilation.

## Key findings

- Primordial black holes in the mass range 10^{16}-10^{17} g are constrained as dark matter candidates.
- Models with PBHs making up all dark matter in this mass range are ruled out.
- The method provides a new observational constraint on PBH dark matter scenarios.

## Abstract

Models in which dark matter consists entirely of primordial black holes (PBHs) with masses around $10^{17}$ g are currently unconstrained. However, if PBHs are a component of the Galactic dark matter density, they will inject a large flux of energetic particles into the Galaxy as they radiate. Positrons produced by these black holes will subsequently propagate throughout the Galaxy and annihilate, contributing to the Galactic 511 keV line. Using measurements of this line by the INTEGRAL satellite as a constraint on PBH positron injection, we place new limits on PBH abundance in the mass range $10^{16} - 10^{17}$ g, ruling out models in which these PBHs constitute the entirety of dark matter.