Cosmological Consequences of Exponential Gravity in Palatini Formalism

TL;DR

This paper explores exponential $f(R)$ gravity in the Palatini formalism, showing it can produce transient acceleration and a viable cosmological history consistent with observations.

Contribution

It introduces a novel exponential $f(R)$ gravity model in the Palatini formalism and constrains its parameters using supernova and high-redshift data.

Findings

The model predicts transient acceleration with future deceleration.

It fits current cosmological data well.

Certain parameter ranges yield a standard matter-to-acceleration transition.

Abstract

We investigate cosmological consequences of a class of exponential $f(R)$ gravity in the Palatini formalism. By using the current largest type Ia Supernova sample along with determinations of the cosmic expansion at intermediary and high-$z$ we impose tight constraints on the model parameters. Differently from other $f(R)$ models, we find solutions of transient acceleration, in which the large-scale modification of gravity will drive the Universe to a new decelerated era in the future. We also show that a viable cosmological history with the usual matter-dominated era followed by an accelerating phase is predicted for some intervals of model parameters.