Dense Stellar Matter with Strange Quark Matter Driven by Kaon Condensation

TL;DR

This paper investigates a three-phase model of neutron-star matter, including nuclear, kaon-condensed, and strange quark phases, proposing a smooth transition that aligns with recent mass-radius observational constraints.

Contribution

It introduces a simplified model connecting nuclear, kaon-condensed, and quark matter phases in neutron stars, compatible with observed stellar mass constraints.

Findings

The model supports a smooth phase transition in neutron-star matter.

Equation of state parameters are consistent with the 1.97-solar mass neutron star.

Kaon condensation acts as a bridge to strange quark matter.

Abstract

The core of neutron-star matter is supposed to be at a much higher density than the normal nuclear matter density for which various possibilities have been suggested such as, for example, meson or hyperon condensation and/or deconfined quark or color-superconducting matter. In this work, we explore the implication on hadron physics of a dense compact object that has three "phases", nuclear matter at the outer layer, kaon condensed nuclear matter in the middle and strange quark matter at the core. Using a drastically simplified but not unreasonable model, we develop the scenario where the different phases are smoothly connected with the kaon condensed matter playing a role of "doorway" to a quark core, the equation of state (EoS) of which with parameters restricted within the range allowed by nature could be made compatible with the mass vs. radius constraint given by the 1.97-solar mass object PSR J1614-2230 recently observed.