Holographic Ricci dark energy: Interacting model and cosmological constraints

TL;DR

This paper extends the holographic Ricci dark energy model by incorporating various forms of interaction with dark matter, constrains these models with observational data, and finds evidence for a strong coupling between dark energy and dark matter.

Contribution

It introduces and analytically solves three new interacting holographic Ricci dark energy models and constrains them using recent cosmological observations.

Findings

Interacting models yield more reasonable matter density parameters.

Observations favor a strong coupling between dark energy and dark matter.

Models are consistent with current supernova, CMB, and BAO data.

Abstract

We extend the holographic Ricci dark energy model to include some direct, non-gravitational interaction between dark energy and dark matter. We consider three phenomenological forms for the interaction term $Q$ in the model, namely, $Q$ is taken proportional to the Hubble expansion rate and the energy densities of dark sectors (taken to be $\rho_{\rm de}$, $\rho_{\rm m}$, and $\rho_{\rm de}+\rho_{\rm m}$, respectively). We obtain a uniform analytical solution to the three interacting models. Furthermore, we constrain the models by using the latest observational data, including the 557 Union2 type Ia supernovae data, the cosmic microwave background anisotropy data from the 7-yr WMAP, and the baryon acoustic oscillation data from the SDSS. We show that in the interacting models of the holographic Ricci dark energy, a more reasonable value of $\Omega_{\rm m0}$ will be obtained, and the observations favor a rather strong coupling between dark energy and dark matter.