On white dwarfs and neutron stars in Palatini f(R) gravity

TL;DR

This paper investigates how Palatini f(R) gravity modifies the structure and maximum mass limits of white dwarfs and neutron stars, suggesting astrophysical observations can test alternative gravity theories.

Contribution

It provides numerical solutions for compact objects in specific Palatini f(R) models and assesses their observational implications.

Findings

Density profiles are altered in Palatini f(R) models.

Maximum masses of white dwarfs and neutron stars are affected.

Observations can potentially exclude certain f(R) gravity models.

Abstract

In Palatini $f(R)$ gravity, the parameters of the Schwarzschild - de Sitter solution as well as the whole interior solutions of compact objects are expected to change when compared to general relativity. We solve the Palatini field equations numerically in the case of the models $f(R) = R + \alpha R^2$ and $f(R) = R - \mu^4/R$, and using the equation of state of Fermi gas. We show how the density profiles and the prediction for the maximum masses of white dwarfs (the Chandrasekhar limit) and neutron stars (the Tolman-Oppenheimer-Volkoff limit) are altered, and thereby conclude that observations on compact stars may be used to exclude alternative gravity models.