How the HESS J1731-347 event could be explained using $\bf{K^{-}}$ condensation

TL;DR

This paper explores the potential presence of kaon condensation in neutron stars, specifically in HESS J1731-347, using two different theoretical models to better understand dense nuclear matter properties.

Contribution

It introduces a comparative analysis of kaon condensation in neutron stars employing both the Relativistic Mean Field and Momentum-Dependent Interaction models, a novel approach for this specific object.

Findings

Kaon condensation likely occurs at certain density thresholds.

Model parameters significantly influence the predicted properties.

Insights into the strangeness content of protons are obtained.

Abstract

The recent observation of a compact star with a mass of $M=0.77^{+0.20}_{-0.17}~{\rm M_{\odot}}$ and a radius of $R=10.4^{+0.86}_{-0.78}$ km, located within the supernova remnant HESS J1731-347, has substantially reinforced the evidence for the presence of exotic matter in neutron stars core. This finding has markedly enhanced our comprehension of the equation of state for dense nuclear matter. In the present work, we investigate the possible existence of a kaon condensation in hadronic neutron stars by employing and comparing two theoretical frameworks: the Relativistic Mean Field model with first order kaon condensate and the Momentum-Dependent Interaction model complemented by chiral effective theory. To the best of our knowledge, this represents a first alternative attempt aimed to explain the bulk properties of the specific object with the inclusion of a kaon condensation in dense nuclear matter. The application of two different models enriches the research, providing insights from the aspect of different theoretical frameworks that accurately predict the existence of HESS J1731-347. In both cases significant insights are extracted for the parameter space of models, emphasizing to those concerning the nucleon-kaon potential, the threshold density for the appearance of a kaon condensation, as well as the parameter $a_{3}m_{s}$ which is related to the strangeness content of the proton. Concluding, the present research indicates that a more systematic investigation of similar objects could offer valuable constraints on the properties of dense nuclear matter.