Primordial Black Holes in Matter-Dominated Eras: the Role of Accretion

TL;DR

This paper investigates how accretion processes during matter-dominated eras can lead to the formation and significant growth of primordial black holes, highlighting a potential mechanism for their evolution after initial collapse.

Contribution

It introduces the concept that primordial black holes can form and grow through secondary infall and accretion in matter-dominated periods following inflation.

Findings

Primordial black holes can form via post-collapse accretion.

Accretion can increase black hole masses by orders of magnitude.

Accretion plays a significant role in black hole evolution after inflation.

Abstract

We consider the role of secondary infall and accretion onto an initially overdense perturbation in matter-dominated eras, like the one which is likely to follow the end of inflation. We show that primordial black holes may form through post-collapse accretion, namely the accretion onto an initial overdensity whose collapse has not given rise to a primordial black hole. Accretion may be also responsible for the growth of the primordial black hole masses by orders of magnitude till the end of the matter-dominated era.