Whether Lyra's Manifold Itself is a Hidden Source of Dark Energy

Abstract: In the course of investigation of some interesting cosmic string universes in the five dimensional Lyra manifold it is excitingly found that the geometry itself of Lyra manifold behaves as a new source of dark energy and this energy takes a form similar to that of quintessence in most of the cases, though in one case the dark energy comes out to be that of the cosmological constant type. The behaviour of the universes and their contribution to the process of evolution are examined. Further study of such type of universes will be very helpful in explaining the present accelerated expansion behaviour of the universe.