Bianchi Type- I  Bulk Viscosity with a DE Cosmological Model

Daba Meshesha Gusu,Saibal Ray

doi:10.1155/2020/4015426

Abstract

The finding article presents Bianchi type- I universe in the presence of bulk viscous and DE fluid nature of a cosmological model. The solutions of field equations were obtained by assuming hybrid expansion law. The physical significance of the obtained findings illustrates the dominance of bulk viscosity in early and dominance of dark energy fluid emergences in late. This leads to indicate the presence of bulk viscosity nature more effective in early time rather than late times, and also, it shows the dominance of dark energy in late times which grants the current observational result of the universe. Certain physical and geometrical properties of the model are also discussed.

Highlights

Experimental results of supernovae type-I luminance (Riess et al [1]; Perlmutter et al [2]), peaks of cosmic microwave circumstances (Komatsu et al [3]), oscillations of baryon acoustic (Eisenstein et al [4]), and structures of large scale (Tegmark et al [5]) directed a composition of a universe 70% dark energy (Mendola and Tsujikawa [6]; Frieman et al [7])
The bulk viscosity related to energy density with the help of Hubble’s parameter ðHÞ as 3ζH = ε0ρ, where ε0 is the proportionality constant and 3ζH is usually termed as bulk viscous pressure
I have obtained a Bianchi type-I cosmological model filled with bulk viscous and dark energy (DE) fluid

Summary

Introduction

Experimental results of supernovae type-I luminance (Riess et al [1]; Perlmutter et al [2]), peaks of cosmic microwave circumstances (Komatsu et al [3]), oscillations of baryon acoustic (Eisenstein et al [4]), and structures of large scale (Tegmark et al [5]) directed a composition of a universe 70% dark energy (Mendola and Tsujikawa [6]; Frieman et al [7]). A few years ago, the high redshift supernova experiments (Garnavich et al [8]; Riess et al [1]; Perlmutter et al [2, 9, 10]) and cosmic microwave background radiation (Bennett et al [11]; Riess et al [12]) have provided the necessary evidence for the accelerated expansion of the universe This looks inexplicable as for two reasons: the first one for the indication that there must be an unknown and unusual source of energy which acts as antigravity, in order to produce negative pressure to overcome the attractive force of gravity, and the second one for the gravity of general theory which should be modified. Researchers have contributed a necessity role to bulk viscous fluid matter which is different from the traditional case The effects of both shear and bulk viscosity were explained by Hoogeveen et al [31] using kinetic theory during early time. All above information gives us motivation to investigate Bianchi type-I spacetime bulk viscous fluid with dark energy cosmological model using hybrid scale factor.

The Metric and Field Equations

Solutions of the Field Equations

Some Physical and Geometrical Properties of the Model

Conclusion