Detailed Calculation of Primordial Black Hole Formation During First-Order Cosmological Phase Transitions

TL;DR

This paper investigates the detailed conditions and mechanisms by which primordial black holes could form during first-order cosmological phase transitions, focusing on particle reflection and phase space evolution.

Contribution

It provides a comprehensive analysis of black hole formation criteria and formulates the Boltzmann equation for particle distributions during phase transitions.

Findings

Black holes can form under various scenarios with spherical false vacuum pockets.

The paper derives specific conditions for black hole formation during phase transitions.

A detailed Boltzmann equation framework is established for these processes.

Abstract

Primordial black holes could potentially form during a first-order cosmological phase transition due to a build-up of particles which are predominantly reflected from the advancing bubble walls. After discussing the general mechanism, we examine the criteria that need to be satisfied for a black hole to form. We then set out the Boltzmann equation that describes the evolution of the relevant phase space distribution function, carefully describing our treatment of the Liouville operator and the collision term. Assuming a spherical false vacuum pocket of sufficient size and a constant wall velocity, we find that black holes can form in a range of different scenarios.