Phantom-like behaviour in a brane-world model with curvature effects

TL;DR

This paper investigates whether adding a Gauss-Bonnet term to a brane-world model can extend the phantom-like behavior of the universe, but finds that it instead causes an earlier breakdown of this regime.

Contribution

The study explores the impact of Gauss-Bonnet curvature effects on phantom-like behavior in brane cosmology, revealing that it shortens the validity of the phantom regime.

Findings

Gauss-Bonnet term does not extend phantom regime

Inclusion of GB term causes earlier breakdown of phantom behavior

Curvature effects influence the stability of phantom-like cosmology

Abstract

Recent observational evidence seems to allow the possibility that our universe may currently be under a dark energy effect of a phantom nature. A suitable effective phantom fluid behaviour can emerge in brane cosmology; In particular, within the normal non self-accelerating DGP branch, without any exotic matter and due to curvature effects from induced gravity. The phantom-like behaviour is based in defining an effective energy density that grows as the brane expands. This effective description breaks down at some point in the past when the effective energy density becomes negative and the effective equation of state parameter blows up. In this paper we investigate if the phantom-like regime can be enlarged by the inclusion of a Gauss-Bonnet (GB) term into the bulk. The motivation is that such a GB component would model additional curvature effects on the brane setting. More precisely, our aim is to determine if the GB term, dominating and modifying the early behaviour of the brane universe, may eventually extend the regime of validity of the phantom mimicry on the brane. However, we show that the opposite occurs: the GB effect seems instead to induce a breakdown of the phantom-like behaviour at an even smaller redshift.