Primordial Black Holes as Dark Matter Candidates

TL;DR

This review explores primordial black holes as potential dark matter candidates, discussing their formation, constraints on their mass ranges, and their possible roles in cosmic structure formation and as dark matter components.

Contribution

It provides a comprehensive overview of the formation, constraints, and cosmological implications of primordial black holes as dark matter candidates.

Findings

PBHs could account for dark matter in specific mass windows.

Large PBHs may seed cosmic structures and supermassive black holes.

PBH relics and extremely large black holes are potential dark matter components.

Abstract

We review the formation and evaporation of primordial black holes (PBHs) and their possible contribution to dark matter. Various constraints suggest they could only provide most of it in the mass windows $10^{17}$ - $10^{23}\,$g or $10$ - $10^{2}\,M_{\odot}$, with the last possibility perhaps being suggested by the LIGO/Virgo observations. However, PBHs could have important consequences even if they have a low cosmological density. Sufficiently large ones might generate cosmic structures and provide seeds for the supermassive black holes in galactic nuclei. Planck-mass relics of PBH evaporations or stupendously large black holes bigger than $10^{12}\,M_{\odot}$ could also be an interesting dark component.