Cosmological Black Hole Formation due to QCD and Electroweak Phase Transitions

TL;DR

This paper investigates how QCD and electroweak phase transitions in the early universe influence black hole formation, revealing that first order transitions could lead to a black hole dominated universe regardless of primordial fluctuation parameters.

Contribution

It provides a detailed analysis of the conditions under which early universe phase transitions lead to primordial black hole formation, highlighting the impact of transition order and density fluctuation index.

Findings

First order phase transitions can produce a black hole dominated universe for any fluctuation index.

Second order transitions or rapid crossovers require a fluctuation index n > 1.25 for significant black hole formation.

The study offers a framework to connect early universe phase transitions with present-day black hole distributions.

Abstract

We solve dynamical equations of motion to determine the conditions under which an over-dense region in the early universe will lead to collapse to a black hole, starting from horizon crossing of the over-dense region to the point of gravitational instability. Here we focus on the sensitivity to QCD and electroweak phase transitions. We then solve rate equations to determine the mass distribution of black holes in the present universe. A second order phase transition or rapid crossover would have significant consequences only if the index of primordial density fluctuations n > 1.25. However, a first order transition would lead to a black hole dominated universe for any realistic value of n including n=1.