Constraining the equation of state of hybrid stars using recent information from multidisciplinary physics

TL;DR

This paper constrains the equation of state for hybrid stars by integrating recent nuclear, astrophysical, and quantum chromodynamics data, revealing limits on star properties and the likelihood of quark cores.

Contribution

It systematically applies multidisciplinary constraints to narrow down the EoS parameter space for neutron stars, especially regarding quark matter phases.

Findings

pQCD constraints significantly reduce quark matter model uncertainties

Astrophysical data favor high bag parameter B values

Pure quark matter cores in hybrid stars are disfavored

Abstract

At the ultra-high densities existing in the core of neutron stars, it is expected that a phase transition from baryonic to deconfined quark matter may occur. Such a phase transition would affect the underlying equation of state (EoS) as well as the observable astrophysical properties of neutron stars. Comparison of EoS model predictions with astronomical data from multi-messenger signals then provides us an opportunity to probe the behaviour of dense matter. In this work, we restrict the allowed parameter space of EoS models in neutron stars for both nucleonic (relativistic mean field model) and quark matter (bag model) sectors by imposing state-of-the-art constraints from nuclear calculations, multi-messenger astrophysical data and perturbative QCD (pQCD). We systematically investigate the effect of each constraint on the parameter space of uncertainties using a cut-off filter scheme, as well as the correlations among the parameters and with neutron star astrophysical observables. Using the constraints, we obtain limits for maximum NS mass, maximum central density, as well as for NS radii and tidal deformability. Although pQCD constraints are only effective at very high densities, they significantly reduce the parameter space of the quark model. We also conclude that astrophysical data supports high values of the bag parameter B and disfavors the existence of a pure quark matter core in hybrid stars.