Constraining the bulk viscous coefficients in a viscous universe with cosmological constant

Abstract

In this paper we consider dissipative effects in $\Lambda$CDM model, i.e., we consider a universe with cosmological constant having viscous matter. We assume the most general form for bulk viscous coefficient, $\zeta ={\zeta }_0+{\zeta }_1\frac{\dot{a}}{a}+{\zeta }_2\frac{\ddot{a}}{\dot{a}}$ and obtained various constrains for $\zeta$'s . We also studied the background study of the model with $\zeta ={\zeta }_0$ and $\zeta ={\zeta }_1\frac{\dot{a}}{a}$. Extracted the value of ${\zeta }_1$ using the Pantheon data and also obtained its thermodynamic evolution and the age.

arXiv comment12 pages 5 figures