Emergent cosmology in 4D Einstein Gauss Bonnet theory of gravity
Abstract
In this paper, in an FLRW background and a perfect fluid equation of state, we explore the possibility of the realization of an emergent scenario in a 4D regularized extension of EinsteinGaussBonnet gravity, with the field equations particularly expressed in terms of scalartensor degrees of freedom. By assuming nonzero spatial curvature (k = ± 1), the stability of the Einstein static universe (ESU) and its subsequent exit into the standard inflationary scenario is tested through different approaches. In terms of dynamical systems, a spatially closed universe rather than an open universe shows appealing behaviour to exhibit a graceful transition from the ESU to standard cosmological history. We found that under linear homogeneous perturbations, for some constraints imposed on the model parameters, the ESU is stable under those perturbations. Moreover, it is noted that for a successful graceful transition, the equation of state ω must satisfy the conditions ‑1 < ω < 0 and ω < ‑ 1 for closed and open universes, respectively. Furthermore, the ESU is seen to be neutrally stable under matter perturbation in the Newtonian gauge.
 Publication:

Physica Scripta
 Pub Date:
 July 2024
 DOI:
 10.1088/14024896/ad5238
 arXiv:
 arXiv:2404.01355
 Bibcode:
 2024PhyS...99g5306G
 Keywords:

 4DEinsteinGaussBonnet gravity;
 cosmology;
 emergent cosmology;
 modified gravity;
 einstein static universe;
 General Relativity and Quantum Cosmology
 EPrint:
 12 pages, 2 figures, Accepted in Physica Scripta