General predictions for the neutron star crustal moment of inertia

TL;DR

This paper uses a Bayesian meta-modeling approach to accurately predict neutron star crustal properties, including the crustal moment of inertia, with quantified uncertainties, and discusses implications for pulsar glitches.

Contribution

It introduces a unified Bayesian framework combining nuclear theory and experimental data to improve predictions of neutron star crustal properties with controlled confidence intervals.

Findings

Approximately 11% dispersion on crustal width

Approximately 27% dispersion on fractional moment of inertia

Predictions suggest constraints on crustal entrainment effects for Vela pulsar glitches

Abstract

The neutron star crustal EoS and transition point properties are computed within a unified meta-modeling approach. A Bayesian approach is employed including two types of filters: bulk nuclear properties are controlled from low density effective field theory (EFT) predictions as well as the present knowledge from nuclear experiments, while the surface energy is adjusted on experimental nuclear masses. Considering these constraints, a quantitative prediction of crustal properties can be reached with controlled confidence intervals and increased precision with respect to previous calculations: {$\approx 11\%$} dispersion on the crustal width and {$\approx 27\%$} dispersion on the fractional moment of inertia. The crust moment of inertia is also evaluated as a function of the neutron star mass, and predictions for mass and radii are given for different pulsars. The possible crustal origin of Vela pulsar glitches is discussed within the present estimations of crustal entrainment, disfavoring a large entrainment phenomenon if the Vela mass is above $1.4M_\odot$. Further refinement of the present predictions requires a better estimation of the high order isovector empirical parameters, e.g. $K_{sym}$ and $Q_{sym}$, and a better control of the surface properties of extremely neutron rich nuclei.