Neutron stars in f (R, Lm) gravity with realistic equations of state: joint-constrains with GW170817, massive pulsars, and the PSR J0030+0451 mass-radius from NICER data

In this work, we investigate neutron stars (NS) in f (R, Lm) theory of gravity for the case f (R, L-m) = R + L-m + sigma RLm, where R is the Ricci scalar and Lm the Lagrangian matter density. In the term sigma RLm, sigma represents the coupling between the gravitational and particles fields. For the first time the hydrostatic equilibrium equations in the theory are solved considering realistic equations of state and NS masses and radii obtained are subject to joint constrains from massive pulsars, the gravitationalwave event GW170817 and from the PSR J0030+0451 mass-radius from NASA's Neutron Star Interior Composition Explorer (NICER) data. We show that in this theory of gravity, the mass-radius results can accommodate massive pulsars, while the general theory of relativity can hardly do it. The theory also can explain the observed NS within the radius region constrained by the GW170817 and PSR J0030+0451 observations for masses around 1.4 M-circle dot.

Automated summary

In this study, neutron stars are investigated in f (R, Lm) theory of gravity with the specific case f (R, L-m) = R + L-m + sigma RLm, and the results show that this theory can accommodate massive pulsars and explain observed neutron stars within radius regions constrained by GW170817 and PSR J0030+0451 observations.