Building a realistic neutron star from holography

TL;DR

This paper uses an improved holographic model to construct realistic neutron star models, successfully matching observed mass, radius, and deformability constraints while highlighting current theoretical limitations and future directions.

Contribution

It introduces an enhanced holographic approach incorporating isospin asymmetry, beta equilibrium, and crust modeling, advancing neutron star simulations beyond previous holographic methods.

Findings

Holographic model can produce neutron stars consistent with observational constraints

Crust-core transition can be dynamically determined within the model

Identifies tensions and artifacts in the current parameter fitting

Abstract

We employ the recently improved description of dense baryonic matter within the Witten-Sakai-Sugimoto model to construct neutron stars. In contrast to previous holographic approaches, the presence of an isospin asymmetry allows us to implement beta equilibrium and electric charge neutrality. As a consequence, we are able to model the crust of the star within the same formalism and compute the location of the crust-core transition dynamically. After showing that a simple pointlike approximation for the baryons fails to satisfy astrophysical constraints, we demonstrate that our improved description does account for neutron stars that meet the current experimental constraints for mass, radius, and tidal deformability. However, we also point out tensions in the parameter fit and large-$N_c$ artifacts and discuss how to potentially resolve them in the future.