String Cosmological Models in a Modified Theory of Gravitation

Abstract

This paper deals with the investigation of spatially homogeneous Bianchi type – VI₀ cosmic string models in the modified theory of gravitation proposed by Harko et al. (Phys. Rev. D 84, 02 4020, 2011) which is usually called as f (R, T) gravity.  Here R is the scalar curvature and T is the trace of the energy momentum tensor.  Field equations of this theory are solved using the physical  conditions (i)the shear scalar is proportional to scalar expansion of the space – time and (ii)the equations of state for string models.  The solutions represent the string cosmological models, in this theory, which correspond to the well-known geometric or Nambu string and Takabayasi or p-string.  Some physical and kinematical properties of the models are also discussed.