Observable Signatures of a Quarkyonic Phase in Neutron Stars

TL;DR

This paper uses Bayesian inference to show that quarkyonic matter models for neutron stars fit current observations and proposes a new observational signature involving mass-radius slope and sound speed to identify quarkyonic phases.

Contribution

It introduces a novel observational signature based on mass-radius slope and sound speed to distinguish quarkyonic phases in neutron stars, supported by Bayesian analysis.

Findings

Quarkyonic models satisfy all current astrophysical constraints.

A distinct region in the mass-radius and sound speed plane indicates quarkyonic stars.

Next-generation measurements can test for the presence of quarkyonic phases.

Abstract

Performing Bayesian inference on quarkyonic equation-of-state models for neutron star matter, we find they satisfy all current astrophysical observations, thus reinforcing the argument for the use of such neutron star matter equation-of-state models alongside traditional ones. To observationally differentiate between stars with and without a quarkyonic phase, we identify a novel observational signature: the slope of the mass-radius relation at some fixed mass in conjunction with the sound speed at the star's center. In this plane, we find quarkyonic stars in a region with high central sound speed and positive slope, that is distinct from purely nucleonic stars. High accuracy NS radii measurements facilitated by the next generation of detectors, coupled with ongoing studies of mapping astrophysical observables to microphysical properties like sound speed can be used for testing this signature. Our results indicate that a neutron star with these properties would be a strong evidence for existence of a quarkyonic phase or a similar crossover transition in its core.