Induced gravitational waves and baryon asymmetry fluctuations from primordial black hole formation

TL;DR

This paper explores how large density fluctuations during reheating can lead to primordial black holes, induce gravitational waves, and generate baryon asymmetry fluctuations, linking early universe phenomena with observable signatures.

Contribution

It introduces a model connecting black hole formation, gravitational wave production, and baryon asymmetry fluctuations during a stiff epoch of reheating.

Findings

Constraints on gravitational wave energy density from black hole formation.

Calculation of lepton asymmetry generated by metric perturbations.

Identification of a peak in baryon asymmetry fluctuations on small scales.

Abstract

We consider black hole formation due to the gravitational collapse produced by large density fluctuations during an epoch of reheating with a stiff equation of state and calculate the induced gravitational wave spectrum. By considering the existing bounds on the total energy density of gravitational waves today, we find constraints on the parameter space of this scenario. We also calculate the lepton asymmetry generated by metric perturbations via the chiral gravitational anomaly present in the Standard Model and find that, once the electroweak sphaleron processes have taken place, the large spectrum of scalar perturbations responsible for black hole formation induces a peak in the baryon asymmetry fluctuations on small scales.