# Primordial Black Holes and Co-Decaying Dark Matter

## TL;DR

This paper explores how co-decaying dark matter models can lead to primordial black holes forming in the early universe, potentially accounting for a significant dark matter fraction and explaining LIGO-detected black holes.

## Contribution

It derives the mass fraction and distribution of primordial black holes from co-decaying dark matter models, linking early universe physics to observable black hole phenomena.

## Key findings

- Primordial black holes can constitute a significant fraction of dark matter.
- Black hole masses can be near the solar-mass range, relevant for LIGO detections.
- Models predict a non-monochromatic mass distribution of black holes.

## Abstract

Models of Co-Decaying dark matter lead to an early matter dominated epoch -- prior to BBN -- which results in an enhancement of the growth of dark matter substructure. If these primordial structures collapse further they can form primordial black holes providing an additional dark matter candidate. We derive the mass fraction in these black holes (which is not monochromatic) and consider observational constraints on how much of the dark matter could be comprised in these relics. We find that in many cases they can be a significant fraction of the dark matter. Interestingly, the masses of these black holes can be near the solar-mass range providing a new mechanism for producing black holes like those recently detected by LIGO.