In this paper, it is shown that five dimensional LRS Bianchi type-I string cosmological models do not survive for Geometric and Takabayasi string whereas Barotropic string i.e. ρ = ρ(λ) survives and degenerates string with ρ + λ = 0 in scalar tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. A 113:467, 1986). Further we studied some physical and geometrical properties of the model.

In this paper we constructed five dimensional axially symmetric cosmological model generated by a cloud of strings with particles attached to them in Lyra manifold. Out of the two different cases obtained one case leads to the five dimensional vacuum universe in general theory of relativity while the other case yields a string cosmological model in Lyra manifold. In the cosmic string model we observed that the sum of tension density and rest energy density of strings vanishes and this model is also inflationary.

No abstract

In this paper we have taken an attempt to construct a five dimensional perfect fluid cosmological model within the framework of Lyra manifold. It is found that neither perfect fluid nor dust distributions survive. Finally the exact solutions of the vacuum field equations are obtained.

In this paper, we investigate the generalized Saez-Ballester scalar-tensor theory of gravity via Noether gauge symmetry (NGS) in the background of Bianchi type I cosmological spacetime. We start with the Lagrangian of our model and calculate its gauge symmetries and corresponding invariant quantities. We obtain the potential function for the scalar field in the exponential form. For all the symmetries obtained, we determine the gauge fun-tions corresponding to each gauge symmmetry which include constant and dynamic gauge. We discuss cosmological implications of our model and show that it is compatible with the observational data.