Features of holographic dark energy under combined cosmological constraints

We investigate the observational signatures of the holographic dark-energy models, including both the original model and a model with an interaction term between the dark energy and dark matter. We first delineate the dynamical behavior of such models, especially considering whether they would have a big rip for different parameters; then we use several recent observations, including 182 high-quality type Ia supernovae data observed with the Hubble Space Telescope, the SNLS and ESSENCE surveys, 42 latest Chandra X-ray cluster gas mass fraction, 27 high redshift gamma-ray burst samples, the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, and the CMB shift parameter from the WMAP three-year result to give more reliable and tighter constraints on the holographic dark-energy models. The results of our constraints for the holographic dark-energy model without interaction c = 0.748(-0.009)(+0.108), Omega(m0) = 0.276(-0.016)(+0.017), and for the model with interaction (c = 0.692(-0.107)(+0.135), Omega(m0) = 0.281(-0.017)(+0.017), alpha = -0.006(-0.024)(+0.021), where alpha is an interacting parameter). As these use the Bayesian Evidence as a model-selection criterion to make comparisons. We found that the holographic darkenergy models are mildly favored by the observations as compared to the Lambda CDM model.