Inner crust of neutron stars with mass-fitted Skyrme interaction

TL;DR

This paper models neutron star inner crust properties using a Skyrme interaction, linking core-crust transition parameters to observable quantities like pulsar glitches and star radii.

Contribution

It provides new calculations of transition density, pressure, and crustal moment of inertia fraction using a mass-fitted Skyrme interaction, connecting microscopic nuclear physics to astrophysical observations.

Findings

Maximum crustal moment of inertia fraction is about 3.6%.

Derived a lower limit for Vela pulsar radius: R ≥ 3.69 + 3.44 M/M_sun.

Neutron star masses up to ~2 solar masses are consistent with the model.

Abstract

The mass, radius and crustal fraction of moment of inertia in neutron stars are calculated using $\beta$-equilibrated nuclear matter obtained from Skyrme effective interaction. The transition density, pressure and proton fraction at the inner edge separating the liquid core from the solid crust of the neutron stars are determined from the thermodynamic stability conditions using the KDE0v1 set. The neutron star masses obtained by solving the Tolman-Oppenheimer-Volkoff equations using neutron star matter obtained from this set is able to describe highly massive compact stars $\sim$2$M_{\odot}$. The crustal fraction of the moment of inertia can be extracted from studying pulsar glitches. This fraction is highly dependent on the core-crust transition pressure and corresponding density. These results for pressure and density at core-crust transition together with the observed minimum crustal fraction of the total moment of inertia provide a limit for the radius of the Vela pulsar:$R\geq$ 3.69+3.44 M/$M_{\odot}$. Present calculations suggest that the crustal fraction of the total moment of inertia can be at most 3.6% due to crustal entrainment caused by Bragg reflection of unbound neutrons by lattice ions.