String cosmological model in bianchi type IX inflationary universe with flat potential

Abstract

String cosmology has been investigated in a spatially symmetric Bianchi-IX line element under consideration of flat potential. To illustrate the nonlinear system of field equations an appropriate relation between the metric coefficient and the hybrid expansion law (HEL) for the scalar factor a (t) is considered i.e. a(t) = a 0 t γ 1 e γ 2 t where γ1 and γ2 are the non-negative constants and a 0 denotes current value of a(t). It has been observed that the energy density and particle density diverge initially and become finite for large t. The tension in string clouds tends to infinite when t = 0 and constant value at a large value of t for m>1. The proper volume is also increases with time in exponentially way favorable to inflationary criteria. Expansion and shear infinite large initially and approach to finite value at late time. Some structural aspects of the model and their importance are pointed.