Holographic interacting dark energy in the braneworld cosmology

TL;DR

This paper explores a five-dimensional brane cosmology model with interacting holographic dark energy and bulk matter, analyzing its implications for cosmic evolution and matter-radiation equality.

Contribution

It introduces a unified brane cosmology model with interacting holographic dark energy and bulk matter, examining effective equations of state and decay rates.

Findings

The model cannot transition from non-phantom to phantom dark energy regimes.

The matter-radiation equality redshift matches observational estimates.

A general decay rate for interactions is derived.

Abstract

We investigate a model of brane cosmology to find a unified description of the radiation-matter-dark energy universe. It is of the interacting holographic dark energy with a bulk-holographic matter $\chi$. This is a five-dimensional cold dark matter, which plays a role of radiation on the brane. Using the effective equations of state $\omega^{\rm eff}_{\rm \Lambda}$ instead of the native equations of state $\omega_{\rm \Lambda}$, we show that this model cannot accommodate any transition from the dark energy with $\omega^{\rm eff}_{\rm \Lambda}\ge-1$ to the phantom regime $\omega^{\rm eff}_{\rm \Lambda}<-1$. Furthermore, the case of interaction between cold dark matter and five dimensional cold dark matter is considered for completeness. Here we find that the redshift of matter-radiation equality $z_{\rm eq}$ is the same order as $z^{\rm ob}_{\rm eq}=2.4\times10^{4} \Omega_{\rm m}h^2$. Finally, we obtain a general decay rate $\Gamma$ which is suitable for describing all interactions including the interaction between holographic dark energy and cold dark matter.