The transition of equation of state of effective dark energy in the DGP model with bulk contents

TL;DR

This paper explores how bulk matter in the DGP braneworld model influences the evolution of dark energy's equation of state, enabling it to cross the -1 threshold and match observational data.

Contribution

It demonstrates that including bulk matter T^5_5 allows the DGP model to realize the w_{eff} crossing -1, which pure models cannot achieve.

Findings

Bulk matter T^5_5 enables w_{eff} crossing -1.

The model aligns with super-acceleration observations.

Bulk-brane energy exchange alone does not produce the crossing.

Abstract

We investigate the effect of the bulk contents in the DGP braneworld on the evolution of the universe. We find that although the pure DGP model cannot accommodate the transition of the effective equation of state of dark energy, once the bulk matter T^5_5 is considered, the modified model can realize the w_{eff} crossing -1. However this transition of the equation of state cannot be realized by just considering bulk-brane energy exchange or the GB effect while the bulk matter contribution is not included. T^5_5 plays the major role in the modified DGP model to have the w crossing -1 behavior. We show that our model can describe the super-acceleration of our universe with the equation of state of the effective dark energy and the Hubble parameter in agreement with observations.