A New Exponential Gravity

TL;DR

This paper introduces a new exponential f(R) gravity model that explains late-time cosmic acceleration, mimics DM at high curvature, and exhibits oscillating dark energy behavior crossing the phantom divide.

Contribution

It proposes a novel exponential f(R) gravity model with specific parameters that is cosmologically viable, evades local gravity constraints, and features distinctive oscillating dark energy dynamics.

Findings

Model behaves like DM at high curvature

Dark energy equation of state oscillates and crosses -1

Model is distinguishable for 3<n and mbda

Abstract

We propose a new exponential f(R) gravity model with f(R)=(R-\lambda c)e^{\lambda(c/R)^n} and n>3, \lambda\geq 1, c>0 to explain late-time acceleration of the universe. At the high curvature region, the model behaves like the \LambdaCDM model. In the asymptotic future, it reaches a stable de-Sitter spacetime. It is a cosmologically viable model and can evade the local gravity constraints easily. This model share many features with other f(R) dark energy models like Hu-Sawicki model and Exponential gravity model. In it the dark energy equation of state is of an oscillating form and can cross phantom divide line \omega_{de}=-1. In particular, in the parameter range 3< n\leq 4, \lambda \sim 1, the model is most distinguishable from other models. For instance, when n=4, \lambda=1, the dark energy equation of state will cross -1 in the earlier future and has a stronger oscillating form than the other models, the dark energy density in asymptotical future is smaller than the one in the high curvature region. This new model can evade the local gravity tests easily when n>3 and \lambda>1.