We consider an extension of the holographic Ricci dark energy model by introducing an interaction between dark energy and matter. In this model, the dark energy density is given by ${\rho }_{\Lambda }=-\frac{1}{2}\alpha M_p^2\mathcal{R}$, where $\mathcal{R}$ is the Ricci scalar curvature, $M_p$ is the reduced Planck mass, and $\alpha$ is a dimensionless parameter. The interaction rate is given by $Q=\gamma H{\rho }_{\Lambda }$, where $H$ is the Hubble expansion rate, and $\gamma$ is a dimensionless parameter. We investigate current observational constraints on this model by applying the type Ia supernovae, the baryon acoustic oscillation and the cosmic microwave background anisotropy data. It is shown that a nonvanishing interaction rate is favored by the observations. The best fit values are $\alpha =0.45\pm 0.03$ and $\gamma =0.15\pm 0.03$ for the present dark energy density parameter ${\Omega }_{\Lambda 0}=0.73\pm 0.03$.

• Received 28 November 2009

DOI:https://doi.org/10.1103/PhysRevD.81.023519