Non-singular exponential gravity: a simple theory for early- and late-time accelerated expansion

TL;DR

This paper introduces a non-singular exponential gravity theory that unifies early inflation and late-time acceleration, passing local tests, avoiding future singularities, and closely mimicking the standard cosmological model in late times.

Contribution

It proposes a novel exponential gravity model that explains both inflation and dark energy without singularities, and demonstrates its stability and observational consistency.

Findings

Successfully explains early inflation and late acceleration

Avoids future finite-time singularities

Mimics ΛCDM behavior at late times

Abstract

A theory of exponential modified gravity which explains both early-time inflation and late-time acceleration, in a unified way, is proposed. The theory successfully passes the local tests and fulfills the cosmological bounds and, remarkably, the corresponding inflationary era is proven to be unstable. Numerical investigation of its late-time evolution leads to the conclusion that the corresponding dark energy epoch is not distinguishable from the one for the $\Lambda$CDM model. Several versions of this exponential gravity, sharing similar properties, are formulated. It is also shown that this theory is non-singular, being protected against the formation of finite-time future singularities. As a result, the corresponding future universe evolution asymptotically tends, in a smooth way, to de Sitter space, which turns out to be the final attractor of the system.