Neutron star models in frames of f (R) gravity

Abstract

Neutron star models in perturbative f (R) gravity are considered with realistic equations of state. In particular, we consider the FPS and SLy equations of state. The mass-radius relations for f(R) = R+βR(e−R/R0−1) model and for R2 models with cubic corrections are obtained. In the case of R2 gravity with cubic corrections, we obtain that at high central densities (ρ > 10 ρns = 2.7 × 1014 g/cm3 is the nuclear saturation density), stable star configurations exist. The minimal radius of such stars is close to 9 km with maximal mass ∼ 1.9M⊙(SLy equation) or to 8.5 km with mass ∼ 1.7M⊙ (FPS equation). This effect can give rise to more compact stars than in GR. If observationally identified, such objects could constitute a formidable signature for modified gravity at astrophysical level.