Constraints on the inner edge of neutron star crusts from relativistic nuclear energy density functionals

TL;DR

This paper uses relativistic nuclear energy density functionals to analyze the transition density and pressure at the inner edge of neutron star crusts, providing constraints based on experimental data and symmetry energy variations.

Contribution

It offers new constraints on the core-crust transition density and pressure of neutron stars using a carefully calibrated relativistic functional framework.

Findings

Transition density: 0.086-0.090 fm^{-3}

Transition pressure: 0.3-0.76 MeV fm^{-3}

Constraints derived from experimental and symmetry energy data

Abstract

The transition density $n_t$ and pressure $P_t$ at the inner edge between the liquid core and the solid crust of a neutron star are analyzed using the thermodynamical method and the framework of relativistic nuclear energy density functionals. Starting from a functional that has been carefully adjusted to experimental binding energies of finite nuclei, and varying the density dependence of the corresponding symmetry energy within the limits determined by isovector properties of finite nuclei, we estimate the constraints on the core-crust transition density and pressure of neutron stars: $0.086 \ {\rm fm}^{-3} \leq n_t < 0.090 \ {\rm fm}^{-3}$ and $0.3\ {\rm MeV \ fm}^{-3} < P_t \leq 0.76 \ {\rm MeV \ fm}^{-3}$.