Irradiated asymmetric Friedmann branes

TL;DR

This paper studies a brane universe influenced by radiation from a bulk black hole, revealing that radiation pressure and absorption effects compete, but do not alter the universe's recollapse fate.

Contribution

It introduces a model of an asymmetric Friedmann brane with radiation effects, analyzing the interplay of radiation pressure and absorption on brane dynamics.

Findings

Radiation pressure can accelerate the brane, acting like dark energy.

Absorption increases the brane's mass and gravitational attraction.

The Hawking radiation does not prevent the universe's recollapse.

Abstract

We consider a Friedmann brane moving in a bulk impregnated by radiation. The setup is strongly asymmetric, with only one black hole in the bulk. The radiation emitted by this bulk black hole can be reflected, absorbed or transmitted through the brane. Radiation pressure accelerates the brane, behaving as dark energy. Absorption however generates a competing effect: the brane becomes heavier and gravitational attraction increases. We analyse the model numerically, assuming a total absorbtion on the brane for k=1. We conclude that due to the two competing effects, in this asymmetric scenario the Hawking radiation from the bulk black hole is not able to change the recollapsing fate of this brane-world universe. We show that for light branes and early times the radiation pressure is the dominant effect. In contrast, for heavy branes the self-gravity of the absorbed radiation is a much stronger effect. We find the critical value of the initial energy density for which these two effects roughly cancel each other.