Does HESS J1731-347 have a thick crust ?

TL;DR

This paper investigates the internal structure of the neutron star HESS J1731-347 using a relativistic mean-field model with crossing terms, revealing a thick crust due to a mixed-phase core.

Contribution

It introduces a thermodynamically consistent treatment of phase transitions in the CCT model, showing a thick crust in the neutron star's structure.

Findings

Presence of a mixed-phase core extending to the crust

Thick and massive crust in the neutron star

Model successfully explains the properties of HESS J1731-347

Abstract

A relativistic mean-field model with a crossing term of isovector-scalar and isoscalar mesons, the Cracow crossing terms (CCT) model, has previously been shown to be capable of explaining the light and compact object HESS J1731-347. Here, the model is supplemented with a correct treatment of the phase transition. Applying the thermodynamically consistent Gibbs conditions shows that a mixed-phase system occurs in the core of the neutron star over a wide range of densities, extending up to the neutron star crust, leading to an intriguing stellar structure with a thick and massive crust.