Observational constraints on the interacting Ricci dark energy model

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) = -1/2 alpha(MpR)-R-2, where 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 +/- 0.03 and gamma = 0.15 +/- 0.03 for the present dark energy density parameter Omega(Lambda 0) = 0.73 +/- 0.03.