Curvature Late-Time Acceleration in an Eternal Universe

TL;DR

This paper proposes a modified FLRW universe model with anisotropic scaling and broken covariance, leading to nonsingular bounces and late-time acceleration driven by spatial curvature without a cosmological constant, predicting an eternal universe with eventual recollapse.

Contribution

It introduces a novel cosmological model with anisotropic scaling and broken covariance that explains late-time acceleration without dark energy, predicting an eternal universe with recollapse.

Findings

The model achieves late-time acceleration without a cosmological constant.

It predicts an eternal universe with recollapse at specific redshifts.

The model incorporates nonsingular bounces in the early universe.

Abstract

We construct a FLRW universe considering an anisotropic scaling between space and time at extremely high and low energies only. In this context, Friedmann equations contain an additional term arising from spatial curvature which implements nonsingular bounces in the early Universe. The matter content of the model is a nonrelativistic pressureless perfect fluid and radiation. By breaking covariance diffeomorphism also at extreme large scales, an additional term furnishes late-time acceleration due to spatial curvature so that a cosmological constant is not needed. In order to probe the final fate of the universe we also introduce a lower order curvature term which dominates in deep IR. Given the observational parameters we obtain a concrete model in eternal recurrence in which the end of late-time acceleration takes place at a redshift $z \simeq -0.14$ and the universe recollapses at $z\simeq - 0.32$.