Does emergent scenario in Hořava–Lifshitz gravity demand a ghost field?

Abstract

The non-singular model of the Universe i.e. emergent scenario is now very well known in cosmology. In Einstein gravity such type of singularity free solution is possible in the context of non-equilibrium thermodynamical prescription (both in first and 2nd order theory) with particle creation mechanism. Also there are various models of emergent scenario in different gravity theories. The present work is a twofold attempt namely (i) it has been examined whether it is possible to have singularity free solution in Hořava-Lifshitz modified gravity theory, (ii) if such singularity free solution exists then whether such solution is thermodynamically viable. It is found that perfect fluid matter distribution with phantom nature can generate such type of solution for closed and flat model. Finally thermodynamical analysis has been studied both at the apparent horizon and at any arbitrary horizon.

Does diffusion mechanism favor the emergent scenario of the universe?

“…In the present work, for non-singular solution we shall consider the model of emergent scenario as it is very much relevant as pre-inflationary era. An emergent Universe [12][13][14][15][16][17][18] is a modelled Universe with no time like singularity having static Einstein era in the infinite past (i.e. t → −∞).…”

Cyclic evolution in a two fluid diffusive Universe

“…Second law of thermodynamics insists that any system interacting with thermal energy converts a fraction of heat into the corresponding amount of . Now in a bouncing Universe, near emergent stage [7][8][9][10][11][12][13], t → ±∞, a → b 0 (a constant), H → 0, h ∼ constant. Also at, t = t, H = 0, γ = 0, where t is the transition time epoch from expansion to contracting phase.So, the primitive choice (after trials with several different choices ) is taken as,…”