Higher Dimensional Bianchi Type-I Cosmological Models With Massive String in General Relativity

Kangujam Priyokumar Singh,Jiten Baro,Asem Jotin Meitei

doi:10.3389/fspas.2021.777554

Abstract

Here we studied Bianchi type-I cosmological models with massive strings in general relativity in five dimensional space time. Out of the two different cases obtained here, one case leads to a five dimensional Bianchi type-I string cosmological model in general relativity while the other yields the vacuum Universe in general relativity in five dimensional space time. The physical and geometrical properties of the model Universe are studied and compared with the present day’s observational findings. It is observed that our model is anisotropic, expanding, shearing, and decelerates at an early stage and then accelerates at a later time. The model expands along x, y, and z axes and the extra dimension contracts and becomes unobservable at t → ∞. We also observed that the sum of the energy density (ρ) and the string tension density (λ) vanishes (ρ + λ = 0).

Highlights

Nowadays, there has been drastic interest in string cosmology because of its important role in the study of the origin of the Universe and its very early phases before the formation of particles
We found that our Universe is homogeneous and isotropic on a large scale, no physical evidence denies the chance of an anisotropic Universe
Bianchi type-III cosmological models in five-dimensional space-time in general relativity with massive string as an origin of gravitational field were constructed by Samanta et al (Samanta et al, 2011)

Summary

INTRODUCTION

There has been drastic interest in string cosmology because of its important role in the study of the origin of the Universe and its very early phases before the formation of particles. Mohanty and Samanta (Mohanty and Samanta, 2010a) constructed an LRS Bianchi type-I inflationary string cosmological model in five-dimensional space-time with massive scalar field in general relativity and obtained that the sum of energy density and tension density is zero. Bianchi type-III cosmological models in five-dimensional space-time in general relativity with massive string as an origin of gravitational field were constructed by Samanta et al (Samanta et al, 2011). The above discussion motivated us to investigate here the fivedimensional string cosmological models with particles attached to them in Bianchi type-I space-time in general relativity to investigate the different possibilities of the Bianchi type model Universe which transitions from anisotropic in early evolution to isotropic at a later time point where the survival field equations are solved by making some simplifying assumptions. The physical and geometrical properties of some parameters of our model Universe are discussed in detail

THE METRIC AND FIELD EQUATIONS

SOLUTION OF THE FIELD EQUATIONS

PHYSICAL INTERPRETATIONS OF THE SOLUTIONS