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

Abstract

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 $$f(R,L)=R/2+[1+\sigma R]L$$ f(R,L)=R/2+[1+σR]L , with $$\sigma $$ σ constant. To describe matter inside neutron stars we assume a relativistic polytropic equation of state $$p=K \rho ^{\gamma }$$ p=Kργ , with $$\rho $$ ρ being the energy density, K and $$\gamma = 5/3 $$ γ=5/3 being constants. We also consider the more realistic equation of state (EoS) known as SLy4, which is a Skyrme type one based on effective nuclear interaction. We show that in this theory it is possible to reach the mass of massive pulsars, such as PSR J2215 + 5135, for both equations of state. Also, results for mass-radius relation in GMC gravity are strongly dependent on the stiffness of the EoS.