Nuclear constraints on the momenta of inertia of neutron stars

TL;DR

This paper uses nuclear physics constraints from heavy-ion collision experiments to narrow down the equation of state of neutron-rich matter, enabling more precise estimates of neutron star properties like the moment of inertia.

Contribution

It provides new constraints on the neutron star moment of inertia and crust-core transition density based on terrestrial nuclear physics data.

Findings

Moment of inertia of PSR J0737-3039 between 1.30 and 1.63 x 10^45 g cm^2

Crust-core transition density between 0.091 and 0.093 fm^{-3}

Nuclear physics constraints improve neutron star modeling

Abstract

Properties and structure of neutron stars are determined by the equation of state (EOS) of neutron-rich stellar matter. While the collective flow and particle production in relativistic heavy-ion collisions have constrained tightly the EOS of symmetric nuclear matter up to about five times the normal nuclear matter density, the more recent experimental data on isospin-diffusion and isoscaling in heavy-ion collisions at intermediate energies have constrained considerably the density dependence of the nuclear symmetry energy at subsaturation densities. Although there are still many uncertainties and challenges to pin down completely the EOS of neutron-rich nuclear matter, the heavy-ion reaction experiments in terrestrial laboratories have limited the EOS of neutron-rich nuclear matter in a range much narrower than that spanned by various EOSs currently used in astrophysical studies in the literature. These nuclear physics constraints could thus provide more reliable information about properties of neutron stars. Within well established formalisms using the nuclear constrained EOSs we study the momenta of inertia of neutron stars. We put the special emphasis on the component A of the extremely relativistic double neutron star system PSR J0737-3039. Its moment of inertia is found to be between 1.30 and 1.63 $(\times10^{45}g$ $cm^2)$. Moreover, the transition density at the crust-core boundary is shown to be in the narrow range of $\rho_t=[0.091-0.093](fm^{-3})$.