Neutron stars in $$f(R,L_m,T)$$ f ( R , L m , T ) gravity

Abstract

Abstract This study explores the behavior of compact stars within the framework of $$f(R,L_m,T)$$ f ( R , L m , T ) gravity, focusing on the functional form $$f(R,L_m,T) = R + \alpha TL_m$$ f ( R , L m , T ) = R + α T L m . The modified Tolman–Oppenheimer–Volkoff (TOV) equations are derived and numerically solved for several values of the free parameter $$\alpha $$ α by considering both quark and hadronic matter—described by realistic equations of state (EoSs). Furthermore, the stellar structure equations are adapted for two different choices of the matter Lagrangian density (namely, $$L_m= p$$ L m = p and $$L_m= -\rho $$ L m = - ρ ), laying the groundwork for our numerical analysis. As expected, we recover the traditional TOV equations in General Relativity (GR) when $$\alpha \rightarrow 0$$ α → 0 . Remarkably, we found that the two choices for $$L_m$$ L m have appreciably different effects on the mass-radius diagrams. Results showcase the impact of $$\alpha $$ α on compact star properties, while final remarks summarize key findings and discuss implications, including compatibility with observational data from NGC 6397’s neutron star. Overall, this research enhances comprehension of $$f(R,L_m,T)$$ f ( R , L m , T ) gravity’s effects on compact star internal structures, offering insights for future investigations.