$\gamma$ gravity: Steepness control

TL;DR

This paper introduces a generalized $f(R)$ gravity model with a steep dependence on Ricci scalar R, which is compatible with cosmological and solar system tests, and can be distinguished from a cosmological constant in future observations.

Contribution

It proposes a new $f(R)$ gravity model with steep R dependence that aligns with observational constraints and offers potential for future differentiation from dark energy models.

Findings

Model is compatible with solar system tests.

Facilitates agreement with structure formation constraints.

Potential to distinguish from cosmological constant in future surveys.

Abstract

We investigate a simple generalization of the metric exponential $f(R)$ gravity theory that is cosmologically viable and compatible with solar system tests of gravity. We show that, as compared to other viable $f(R)$ theories, its steep dependence on the Ricci scalar $R$ facilitates agreement with structure constraints, opening the possibility of $f(R)$ models with equation-of-state parameter that could be differentiated from a cosmological constant ($w_{de}=-1$) with future surveys at both background and perturbative levels.