Neutron stars and phase diagram from a double hard-wall

TL;DR

This paper uses a simple holographic double hard-wall model to study neutron star cores, revealing a quarkyonic phase, and producing mass-radius relations and equations of state that align closely with observations.

Contribution

It introduces a novel holographic approach with a double hard-wall model to describe neutron star matter, including a quarkyonic phase, and matches observational data.

Findings

Identification of a quarkyonic phase in the model

Mass-radius relations close to observational bounds

A stiff equation of state for neutron star matter

Abstract

Description of nuclear matter in the core of neutron stars eludes the main tools of investigation of QCD, such as perturbation theory and the lattice formulation of the theory. Recently, the application of the holographic paradigm (both via top-down and bottom-up models) to this task has led to many encouraging results, both qualitatively and quantitatively. We present our approach to the description of neutron star cores, relying on a simple model of the (double) hard-wall type: we discuss results concerning the nature of homogeneous nuclear matter at high density emerging from the model including a quarkyonic phase, the mass-radius relation for neutron stars, as well as the rather stiff equation of state we have found. We show how, despite the very simple model employed, for an appropriate calibration we are able to obtain neutron stars that only slightly fall short of the observational bounds on radius and tidal deformability.