Origin and growth of primordial black holes

TL;DR

This paper presents a detailed model of primordial black hole formation and growth, explaining how early universe conditions can produce supermassive black holes with a lower mass limit, using exact solutions to Einstein's equations.

Contribution

It provides a comprehensive, exact metric-based description of primordial black hole evolution from formation to growth, including a novel enhancement effect for horizon formation.

Findings

Explains the origin of early supermassive black holes.

Predicts a lower mass limit for supermassive black holes.

Shows the growth process through radiation and matter phases.

Abstract

Building on the insight that primordial black holes can arise from the formation and subsequent gravitational collapse of bound states of stable supermassive elementary particles during the early radiation era, we offer a comprehensive picture describing the evolution and growth of the resulting mini-black holes through both the radiation and matter dominated phases, until the onset of (small scale) inhomogeneities. This is achieved by means of an exact metric solving Einstein's equations throughout both phases. We show that, thanks to a special enhancement effect producing an effective horizon above the actual event horizon, this process can explain the observed mass values of the earliest giant black holes. Unlike other proposals, it also predicts a lower limit on the mass of supermassive black holes.