  In this paper, a holographic dark energy model, dubbed Ricci dark energy, is
confronted with cosmological observational data from type Ia supernovae (SN
Ia), baryon acoustic oscillations (BAO) and cosmic microwave background (CMB).
By using maximum likelihood method, it is found out that Ricci dark energy
model is a viable candidate of dark energy model with the best fit parameters:
$\Omega_{m0}=0.34\pm 0.04$, $\alpha=0.38\pm 0.03$ with $1\sigma$ error. Here,
$\alpha$ is a dimensionless parameter related with Ricci dark energy $\rho_{R}$
and Ricci scalar $R$, i.e., $\rho_{R}\propto \alpha R$.

Astrophysics