Power Law Inflation and the Cosmic No Hair Theorem in Brane World

TL;DR

This paper investigates how brane world models influence the cosmic no hair theorem, showing that anisotropic universes become isotropic faster during inflation compared to general relativity, due to modifications in Einstein's equations.

Contribution

It demonstrates that brane world modifications accelerate isotropization during inflation and identifies cases where brane effects enable power law inflation not possible in standard theory.

Findings

Anisotropic Bianchi models tend to isotropize faster in brane world scenarios.

Brane modifications facilitate quick transition to isotropy from anisotropy.

Certain inflationary solutions are only possible with brane world modifications.

Abstract

The Cosmic no hair theorem is studied in anisotropic Bianchi brane models which admit power law inflation with a scalar field. We note that all Bianchi models except Bianchi type IX transit to an inflationary regime and the anisotropy washes out at a later epoch. It is found that in the brane world, the anisotropic universe approaches the isotropic phase via inflation much faster than that in the general theory of relativity. The modification in the Einstein field equations on the brane is helpful for a quick transition to an isotropic era from the anisotropic brane. We note a case where the curvature term in the field equation initially drives power law inflation on the isotropic brane which is however not permitted without the brane framework.