If Gauss-Bonnet interaction plays the role of dark energy

Abstract

Gauss-Bonnet-scalar interaction has been found to play a crucial role from the beginning till the late time of cosmological evolution. A cosmological model has been constructed where the Universe starts with exponential expansion but with infinite deceleration (q), and infinite equation of state (w) parameters. During evolution it passes through the stiff fluid era, q=2, w=1, the radiation dominated era, q=1, w=1/3 and the matter dominated era, q=1/2, w=0. Finally, deceleration halts, q=0, w=-1/3, and it then encounters a transition to the accelerating phase. Asymptotically the Universe reaches yet another inflationary phase as q and w go over to -1. Such evolution is independent of the form of the potential and the sign of the kinetic energy term ie., even a noncanonical kinetic energy is unable to phantomize (w<-1) the model.