Sensitivity of the Moment of Inertia of Neutron Stars to the Equation of State of Neutron-Rich Matter

TL;DR

This study investigates how the neutron star's moment of inertia, especially the crustal component, depends on the poorly constrained equation of state of neutron-rich matter, using relativistic models and analyzing the impact of symmetry energy and transition pressure.

Contribution

It demonstrates that the crustal moment of inertia's sensitivity to the symmetry energy is limited, challenging assumptions about their correlation.

Findings

Crustal moment of inertia is highly sensitive to transition pressure.

No significant correlation between symmetry energy density dependence and crustal moment of inertia.

Constraining symmetry energy via neutron skin thickness does not bound crustal properties.

Abstract

The sensitivity of the stellar moment of inertia to the neutron-star matter equation of state is examined using accurately-calibrated relativistic mean-field models. We probe this sensitivity by tuning both the density dependence of the symmetry energy and the high density component of the equation of state, properties that are at present poorly constrained by existing laboratory data. Particularly attractive is the study of the fraction of the moment of inertia contained in the solid crust. Analytic treatments of the crustal moment of inertia reveal a high sensitivity to the transition pressure at the core-crust interface. This may suggest the existence of a strong correlation between the density dependence of the symmetry energy and the crustal moment of inertia. However, no correlation was found. We conclude that constraining the density dependence of the symmetry energy - through, for example, the measurement of the neutron skin thickness in 208Pb - will place no significant bound on either the transition pressure or the crustal moment of inertia.