Bianchi type III cosmological model with hybrid scale factor in the presence of Van der Waals fluid in Lyra manifold

The search for the existence of Lyra manifold in a hybrid universe interacting with Van der Waals fluid using Bianchi type III metric is presented in this paper. To find the exact cosmological solutions, we use certain physical relations between the metric potentials and the average scale factor is assumed to be [Formula: see text] (see Ref. 1) describing the hybrid character of scale factor with the generation of a model of transitioning phase from early decelerating to the present accelerating universe. In this model, when we investigate further about the role of the Van der Waals fluid with Lyra geometry, interestingly, we found that this universe behaves as one containing with dark energy and at the late stage a part of the dark energy behaves as phantom type. This part being generated by the Lyra manifold itself may be taken as a source of dark energy. Some physical as well as geometrical aspects of the model universe are also presented.

Static traversable wormholes in Lyra manifold

At first, considering the Einstein framework, we introduce some new static traversable wormholes and study the effects of a dark energy-like source on them. Thereinafter, a brief review on Einstein field equations in Lyra manifold is presented, and we address some static traversable wormholes in the Lyra manifold which satisfy the energy conditions. It is also shown that solutions introduced in the Einstein framework may also meet the energy conditions in the Lyra manifold. Finally, we focus on vacuum Lyra manifold and find some traversable asymptotically flat wormholes. In summary, our study shows that it is theoretically possible to find a Lyra displacement vector field in a manner in which traversable wormholes satisfy the energy conditions in a Lyra manifold.