Density perturbations in braneworld cosmology and primordial black holes

TL;DR

This paper investigates how scalar perturbations evolve in braneworld cosmology, revealing an amplitude enhancement near horizon crossing that impacts primordial black hole formation, with an approximate solution predicting a constant enhancement factor at high energies.

Contribution

It provides a numerical study of scalar perturbations in Randall-Sundrum braneworld cosmology and introduces an approximate high-energy solution predicting a constant enhancement factor.

Findings

Perturbation amplitudes are enhanced near horizon crossing.

The enhancement factor approaches a constant at high energies.

Implications for primordial black hole production are discussed.

Abstract

We study, by numerical methods, the time evolution of scalar perturbations in radiation era of Randall-Sundrum braneworld cosmology. Our results confirm an existence of the enhancement of perturbation amplitudes (near horizon crossing), discovered recently. We suggest the approximate solution of equations of the perturbation theory in the high energy regime, which predicts that the enhancement factor is asymptotically constant, as a function of scale. We discuss the application of this result for the problem of primordial black hole production in braneworld cosmology.