# Stellar equilibrium configurations of white dwarfs in the $f(R,T)$ gravity

## TL;DR

This paper explores how a modified gravity theory, $f(R,T)$ gravity, affects the structure and maximum mass of white dwarfs, revealing larger radii and masses compared to standard gravity, with potential observational implications.

## Contribution

It introduces the hydrostatic equilibrium equation in $f(R,T)$ gravity and analyzes its impact on white dwarf properties, extending previous models beyond General Relativity.

## Key findings

- White dwarfs can be more massive and larger in $f(R,T)$ gravity.
- Maximum white dwarf mass exceeds the Chandrasekhar limit slightly.
- A lower limit for the parameter $oldsymbol{ extit{ extlambda}}$ is established as $oldsymbol{ extgreater -3 imes 10^{-4}}$.

## Abstract

In this work we investigate the equilibrium configurations of white dwarfs in a modified gravity theory, na\-mely, $f(R,T)$ gravity, for which $R$ and $T$ stand for the Ricci scalar and trace of the energy-momentum tensor, respectively. Considering the functional form $f(R,T)=R+2\lambda T$, with $\lambda$ being a constant, we obtain the hydrostatic equilibrium equation for the theory. Some physical properties of white dwarfs, such as: mass, radius, pressure and energy density, as well as their dependence on the parameter $\lambda$ are derived. More massive and larger white dwarfs are found for negative values of $\lambda$ when it decreases. The equilibrium configurations predict a maximum mass limit for white dwarfs slightly above the Chandrasekhar limit, with larger radii and lower central densities when compared to standard gravity outcomes. The most important effect of $f(R,T)$ theory for massive white dwarfs is the increase of the radius in comparison with GR and also $f(R)$ results. By comparing our results with some observational data of massive white dwarfs we also find a lower limit for $\lambda$, namely, $\lambda >- 3\times 10^{-4}$.