Emergent universe from EnergyMomentum Squared Gravity
Abstract
In order to bypass the big bang singularity, we develop an emergent universe scenario within a covariant extension of General Relativity known as "EnergyMomentum Squared Gravity". The extra terms of the model emerge in the high energy regime. Considering dynamics in a FriedmannLemaîtreRobertsonWalker background, critical points, representing stable Einstein static states of the phase space, result as solutions. It then turns out that as the equation of state parameter ω gradually declines from a constant value as t →  ∞ , eventually some of the static past eternal solutions find the chance to naturally enter into thermal history through a graceful exit mechanism. In this way, the successful realization of the emergent universe allows an expanding thermal history without the big bang singularity for the spatially flat universe free of cosmological constant.
 Publication:

Physics of the Dark Universe
 Pub Date:
 June 2022
 DOI:
 10.1016/j.dark.2022.101013
 arXiv:
 arXiv:2203.13496
 Bibcode:
 2022PDU....3601013K
 Keywords:

 Modified gravity;
 Initial singularity;
 Dynamical systems;
 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Theory
 EPrint:
 18 pages, 9 figures, accepted for publication in "Physics of the Dark Universe"