Observational constraints on cosmic parameters of holographic dark energy model with varying interaction

Abstract

The property of dark energy, which is predicted as the physical reason for the accelerated expansion of the present universe and the coincidence problem by which are suppressed many dark energy models are two of the most difficult problems in modern cosmology. From the Wilkinson Microwave Anisotropy Probe (WMAP) the dark energy contributes about 73% of the total energy of the present universe. Also, the observations of type Ia supernovae (SNIa) suggest that the dark energy which have a huge negative pressure, yields to the transition of the universe from a deceleration to an acceleration phase at some redshift. We use the observation data for the SNIa, Cosmic Microwave Background (CMB) shift parameter, Baryonic Acoustic Oscillations (BAO) peak parameters and Hubble parameters to the transition of the universe and the consideration of the coincidence problem. In this work we reconstruct the interaction between HDE and DM, in which the coupling parameter is parameterized by the well-known Wetterich parameterization and is considered the evolution of the dark matter energy density. Our calculations show that the accurately calculated transition redshift is $z_{t} = 0.89$ in the obtained model. We also calculate the present deceleration parameter $q_{0}$ (−0.92) and resolve the coincidence problem.