Theoretical and observational constraints of viable f(R) theories of gravity

TL;DR

This paper examines the theoretical viability and observational constraints of Hu-Sawicki f(R) gravity models, aiming to identify parameter ranges that allow late-time cosmic acceleration while avoiding singularities.

Contribution

It provides a combined theoretical and observational analysis of Hu-Sawicki f(R) models, constraining their parameters for realistic cosmological behavior.

Findings

Identified parameter ranges avoiding cosmological singularities.

Constrained model parameters using Supernovae Ia data.

Demonstrated conditions for late-time cosmic acceleration.

Abstract

Modified gravity has attracted much attention over the last few years and remains a potential candidate for dark energy. In particular, the so-called viable f(R) gravity theories, which are able to both recover General Relativity (GR) and produce late-time cosmic acceleration, have been widely studied in recent literature. Nevertheless, extended theories of gravity suffer from several shortcomings which compromise their ability to provide realistic alternatives to the standard cosmological Lambda CDM Concordance model. We address the existence of cosmological singularities and the conditions that guarantee late-time acceleration,assuming reasonable energy conditions for standard matter in the so-called Hu-Sawicki f(R) model, currently among the most widely studied modifications to General Relativity. Then using the Supernovae Ia Union 2.1 catalogue, we further constrain the free parameters of this model. The combined analysis of both theoretical and observational constraints sheds some light on the viable parameter space of these models and the form of the underlying effective theory of gravity.