Bayesian inference of quark star equation of state using the NICER PSR J0030+0451 data

TL;DR

This paper uses Bayesian methods to analyze NICER data for PSR J0030+0451, constraining the quark star equation of state and estimating maximum mass and radius, highlighting differences from neutron star models.

Contribution

It introduces a Bayesian framework applying various bag models to quark stars using NICER data, providing new constraints on their maximum mass and radius.

Findings

Maximum quark star mass around 2.38 solar masses

Canonical 1.4 solar mass quark star radius approximately 12.3 km

Quark star radii are smaller than neutron star models

Abstract

We constrain the equation of state of quark stars within the Bayesian statistical approach using the mass and radius measurements of PSR J0030+0451 from NICER. Three types of bag models, with and without non-zero finite quark mass and/or superfluidity, are employed for quark stars made up with self-bound strange quark matter. We find the $90\%$ posterior credible boundary around the most probable values of the quark star maximum mass is $M_{\rm TOV}=2.38_{-0.23}^{+0.26}\,M_{\odot}$, within the model flexibility of the finite quark mass, the quark pairing gap, and the perturbative contribution from the one-gluon exchange. The radius of a canonical $1.4\,M_{\odot}$ quark star is $R_{\rm 1.4}\sim12.3\,{\rm km}$, smaller than the results based on neutron star models.