Viscous fluid cosmology: A path to cosmic acceleration

Abstract

In this study we consider three different cases for bulk viscous fluids, to investigate its coefficients in the background of four dimensional Einstein-Gauss–Bonnet gravity. For this purpose, we assume a bulk viscous matter in a Flat Friedmann-Lemaître-Robertson-Walker metric and derived the associated field equations that govern our system.We approximate the parameter and bulk viscosity coefficient values using set of data taken from BAO, Pantheon and $H\left(z\right)$. We then investigate the asymptotic nature of our model using the phase space analysis. Our model successfully captures the progression of the cosmos from a matter-dominated decelerated era to a uniform de-sitter accelerated era for our considered cases. Additionally, we investigate the physical behavior of the parameters involved in state finder, pressure exerted by different components of universe, and the equation of state (EoS). We examine that accelerated expansion era is accurately detected by the effective EoS parameter, $4D$ Einstein-Gauss–Bonnet parameters and surface pressure component, which exhibit negative behavior in the existence of bulk viscosity.