Dark Energy Coupled with Dark Matter in Viscous Fluid Cosmology

TL;DR

This paper explores cosmological models with interacting dark energy and dark matter in a viscous fluid framework, analyzing their properties and thermodynamical corrections in scenarios like Little Rip, Pseudo Rip, and bounce universes.

Contribution

It introduces analytic representations of viscous cosmological models with dark energy and dark matter interaction, including thermodynamical corrections and characteristic properties.

Findings

Derived analytic forms of bulk viscosity as functions of Hubble parameter and time.

Identified thermodynamical parameter corrections due to fluid-dark matter coupling.

Analyzed properties of Little Rip, Pseudo Rip, and bounce universe scenarios.

Abstract

We investigate cosmological models with two interacting fluids: dark energy and dark matter in flat Friedmann-Robertson-Walker universe. The interaction between dark energy and dark matter is described in terms of the parameters present in the inhomogeneous equation of state when allowance is made for bulk viscosity, for the Little Rip, the Pseudo Rip, and the bounce universes. We obtain analytic representation for characteristic properties in these cosmological models, in particular the bulk viscosity $\zeta=\zeta(H,t)$ as function of Hubble parameter and time. We discuss the corrections of thermodynamical parameters in the equations of state due coupling between the viscous fluid and dark matter. Some common properties of these corrections are elucidated.