Bianchi Type-III Massive String Cosmological Models with Vacuum Energy Density in General Relativity

Abstract

A massive string cosmological model with vacuum energy density in spatially homogeneous and anisotropic Bianchi Type III space-time is investigated. To get the deterministic model of the universe, we assume that the shear (s) is proportional to the expansion (q) which leads to B = Cⁿ and L~1/R³ where B and C are metric potentials, n is a constant and R is scale factor. The models start with a big-bang and the expansion decreases with time. The energy density (r) and string tension density are initially large but decreases with time. The model in general represents anisotropic space and for large values of T, it isotropizes. The first model represents decelerating and accelerating phases of the universe when 2n+1 < 0 and 2n+1> 0 respectively while the special model represents decelerating phase of universe.