Core-crust transition and crustal fraction of moment of inertia in neutron stars

TL;DR

This paper calculates the core-crust transition properties and crustal moment of inertia fraction in neutron stars using a density-dependent M3Y interaction, providing new constraints on neutron star radii based on pulsar glitch data.

Contribution

It introduces a method to determine the core-crust transition density, pressure, and proton fraction using thermodynamic stability, and links these to neutron star radius constraints.

Findings

Transition density: 0.0938 fm$^{-3}$

Transition pressure: 0.5006 MeV fm$^{-3}$

Vela pulsar radius lower limit: 4.10 + 3.36 M/M$_\odot$ km

Abstract

The crustal fraction of moment of inertia in neutron stars is calculated using $\beta$-equilibrated nuclear matter obtained from density dependent M3Y 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 determined from the thermodynamic stability conditions are found to be $\rho_t=$ 0.0938 fm$^{-3}$, P$_t=$ 0.5006 MeV fm$^{-3}$ and $x_{p(t)}=$ 0.0308, respectively. The crustal fraction of the moment of inertia can be extracted from studying pulsar glitches and is most sensitive to the pressure as well as density at the transition from the crust to the core. 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 new limit for the radius of the Vela pulsar: $R \geq 4.10 + 3.36 M/M_\odot$ kms.