Exploring the Equation of State and Properties of Neutron Stars in f(R) Gravity

In addition to a dependence on the Equation of State (EoS) of supranuclear matter, the structure and properties of Neutron Stars (NSs) are sensitive to any modification to strong-field gravity in beyond-GR theories. We computationally explore the relationship between the EoS, theory of gravity, and NS properties by simulating a large variety of NSs. By solving the analogue of the Tolman–Oppenheimer–Volkoff (TOV) equations in f(R) gravity, we obtain the mass-radius relationship of a NS described by any given EoS. In order to search a wide combination of models of gravity and EoSs, we adopt a parameterized f(R) = R + αR² theory and a piecewise-polytropic EoS, which we show is a representative sample of possible EoSs. We developed a GPU-accelerated f(R) TOV solving code in order to rapidly and eciently explore a large parameter space of EoSs and the value of α. We explore correlations between the EoS, α, and the mass-radius relationship, including the prospect for constraints of the EoS and α based on direct observations of NSs and implications for the maximum possible mass of a NS.