String Cosmology in Anisotropic Bianchi-II Space-time

TL;DR

This paper models an anisotropic Bianchi-II universe with massive strings, showing strings dominate early on and vanish later, aligning with observations of an accelerating universe.

Contribution

It develops a new cosmological model with massive strings in Bianchi-II space-time using a specific variation law for the Hubble parameter.

Findings

Massive strings dominate the early universe.

Strings disappear at large times, consistent with observations.

The model accommodates both accelerating and decelerating universe phases.

Abstract

The present study deals with a spatially homogeneous and anisotropic Bianchi-II cosmological model representing massive strings. The energy-momentum tensor, as formulated by Letelier (1983), has been used to construct a massive string cosmological model for which the expansion scalar is proportional to one of the components of shear tensor. The Einstein's field equations have been solved by applying a variation law for generalized Hubble's parameter that yields a constant value of deceleration parameter in Bianchi-II space-time. A comparative study of accelerating and decelerating modes of the evolution of universe has been carried out in the presence of string scenario. The study reveals that massive strings dominate the early Universe. The strings eventually disappear from the Universe for sufficiently large times, which is in agreement with the current astronomical observations.