Insights on Skyrme parameters from GW170817

Abstract

The binary neutron-star merger event, GW170817, has cast a new light on nuclear physics research. Using a neutron-star model that includes a crust equation of state (EoS), we calculate the properties of a 1.4 solar-mass neutron star. The model incorporates more than 200 Skyrme energy density functionals, which describe nuclear matter properties, in the outer liquid core region of the neutron star. We find a power-law relation between the neutron-star tidal deformability, Λ, and the neutron-star radius, R. Without an explicit crust EoS, the model predicts a smaller R and the difference becomes significant for stars with large radii. To connect the neutron star properties with nuclear matter properties, we confront the predicted values for Λ against the Taylor expansion coefficients of the Skyrme interactions. There is no pronounced correlation between Skyrme parameters relevant to symmetric nuclear matter and neutron star properties. However, we find the strongest correlation between Λ and Ksym, the curvature of the density dependence of the symmetry energy at saturation density. At twice the saturation density, our calculations show a strong correlation between Λ and total pressure, providing guidance to laboratory nucleus-nucleus collision experiments. Keywords: Equation of state, Neutron star merger, Skyrme interactions, Tidal polarizability