Hydrostatic equilibrium configurations of neutron stars in a non-minimal geometry-matter coupling theory of gravity

Abstract

In this work we analyze hydrostatic equilibrium configurations of neutron stars in a non-minimal geometry-matter coupling (GMC) theory of gravity. We begin with the derivation of the hydrostatic equilibrium equations for the $f(R,L)$ gravity theory, where $R$ and $L$ are the Ricci scalar and Lagrangian of matter, respectively. We assume $f(R,L)=R/2+[1+\sigma R]L$, with $\sigma$ constant. To describe matter inside neutron stars we assume the polytropic equation of state $p=K{\rho }^{\gamma }$, with $K$ and $\gamma =5/3$ being constants. We show that in this theory it is possible to reach the mass of massive pulsars such as PSR J2215+5135. As a feature of the GMC theory, very compact neutron stars with radius $\sim 8$km and $M\sim 2.6M_{\odot }$ are stable, thus surpassing the Buchdal and Schwarzschild radius limits. Moreover, the referred stellar diameter is obtained within the range of observational data.

EPJC accepted