Rapidly rotating neutron stars in $R$-squared gravity

TL;DR

This paper investigates the properties of rapidly rotating neutron stars within $R^2$ gravity, revealing that rotation amplifies deviations from general relativity and significantly affects neutron star characteristics.

Contribution

It provides a non-perturbative, self-consistent numerical analysis of rotating neutron stars in $R^2$ gravity, advancing understanding of their astrophysical implications.

Findings

Rotation increases deviations from general relativity.

Maximum mass and moment of inertia are significantly higher in $R^2$ gravity.

Results suggest potential observable astrophysical effects.

Abstract

$f(R)$ theories of gravity are one of the most popular alternative explanations for dark energy and therefore studying the possible astrophysical implications of these theories is an important task. In the present paper we make a substantial advance in this direction by considering rapidly rotating neutron stars in $R^2$ gravity. The results are obtained numerically and the method we use is non-perturbative and self-consistent. The neutron star properties, such as mass, radius and moment of inertia, are studied in detail and the results show that rotation magnifies the deviations from general relativity and the maximum mass and moment of inertia can reach very high values. This observation is similar to previous studies of rapidly rotating neutron stars in other alternative theories of gravity, such as the scalar-tensor theories, and it can potentially lead to strong astrophysical manifestations.