On asymptotic behavior of anisotropic Dvali-Gabadadze-Porrati branes

TL;DR

This paper studies the long-term behavior of anisotropic cosmological models in DGP braneworld gravity, showing most models tend to isotropize over time, with some differences in the rate compared to general relativity.

Contribution

It analyzes the asymptotic behavior of anisotropic cosmologies in DGP gravity, extending understanding of isotropization beyond general relativity.

Findings

Most Bianchi models isotropize over time.

Isotropization can be slower than in general relativity.

Type IX models may behave differently.

Abstract

The braneworld model of Dvali-Gabadadze-Porrati (DGP) provides an interesting alternative to a positive cosmological constant by modifying gravity at large distances. We investigate the asymptotic behavior of homogeneous and anisotropic cosmologies on the DGP brane. It is shown that all Bianchi models except type IX isotropize, as in general relativity, if the so called $E_{\mu\nu}$ term satisfies some energy condition. Isotropization can proceed slower in DGP gravity than in general relativity.