New version of viscous Chaplygin gas cosmology with varying gravitational constant

Abstract

In this paper we consider a new version of Chaplygin gas cosmology that includes bulk viscosity and a varying gravitational constant. This new model of Chaplygin gas allows us to recover a barotropic fluid with a quadratic equation of state. Bulk viscosity is assumed to be a power law function of the energy density. We study the evolution of dark energy density numerically for several forms of scale factor and analytically under some assumptions corresponding to a late epoch of the universe. We discuss some cosmological parameters and fix them using recent observational data, such as those from the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) telescope.

Israel-Stewart Approach to Viscous Dissipative Extended Holographic Ricci Dark Energy Dominated Universe

“…Pun et al [30] considered a generalization of the Chaplygin gas model and by assuming the presence of a bulk viscous type dissipative term in the effective thermodynamic pressure of the gas and by considering dissipative effects described by truncated Israel-Stewart model they [30] had shown that viscous Chaplygin gas model offers an effective dynamical possibility for replacing the cosmological constant. Effect of viscosity in Chaplygin gas with different modifications have been studied in [31][32][33]. Cataldo et al [39] investigated dissipative processes in the universe in the full causal Israel-Stewart-Hiscock theory and showed that the negative pressure generated by the bulk viscosity cannot avoid that the dark energy of the universe to be phantom energy.…”