Brane induced cosmological acceleration and crossing of w_{eff}=-1

TL;DR

This paper explores how a five-dimensional braneworld model can produce the observed crossing of the effective equation of state parameter $w_{eff}$ from above to below -1 around redshift 0.2, indicating a transition in cosmic acceleration.

Contribution

It demonstrates that brane-induced cosmological acceleration can account for the crossing of $w_{eff}=-1$, with different behaviors depending on energy exchange between the universe and extra dimension.

Findings

$w_{eff}$ crosses -1 at $z \\sim 0.2$ in the model.

Crossing behavior varies with or without energy exchange.

The model explains the observed variation in cosmic acceleration.

Abstract

The cosmological observation indicates that the effective equation of state parameter $w_{eff}$ varies with $z$: It changes from $w_{eff}>-1$ to $w_{eff}<-1$ at $z\sim 0.2$. We investigate under which condition it exhibits such behaviors based on the five-dimensional braneworld scenario. It is possible in the model with or without an energy exchange between the four dimensional universe and the fifth dimension. However the curves of $w_{eff}$ are quite different between the two cases.