# Spins of primordial binary black holes before coalescence

## TL;DR

This paper investigates how primordial binary black holes can acquire significant spins before merging due to accretion of surrounding matter, especially if they start with high orbital eccentricities.

## Contribution

It introduces a model showing that accretion can spin up primordial black holes prior to coalescence, highlighting the role of initial eccentricities.

## Key findings

- Accretion can significantly increase black hole spins before merger.
- High initial eccentricities enhance spin-up effects.
- Primordial black holes may have observable spins due to accretion.

## Abstract

Primordial stellar-mass black holes, which may contribute to dark matter and to the observed LIGO binary black hole coalescences, are expected to be born with very low spins. Here we show that accretion mass gain by the components of a primordial black hole binary from the surrounding matter could lead to noticeable spins of the components prior to the coalescence provided high initial orbital eccentricities.