Stellar equilibrium configurations of white dwarfs in the f(R,\xa0T) gravity

Abstract

In this work we investigate the equilibrium configurations of white dwarfs in a modified gravity theory, namely, 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+2lambda 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 >- 3times 10^{-4}.