Abstract
We determine, within a meta-model, the properties of the nuclear matter equation of state (EoS) that allow for a phase transition to deconfinement matter. It is shown that the properties that define the isoscalar channel are the ones that are affected, in particular, a phase transition implies much larger values of the skewness and kurtosis. The effect of multi-quark interaction channels in the description of the quark phase in hybrid stars is also studied. NS properties, such as the mass and radius of the quark core, show an interplay dependence between the 8-quark vector and the 4-quark isovector-vector interactions. We show that low mass NS, M ~ 1.4M⊙, may already contain a quark core, and satisfy all existing NS observational constraints. We discuss the strangeness content of the quark core and its influence on the speed of sound.
Highlights
The physics of neutron stars (NS) can be studied by combining astrophysical observations of electromagnetic radiation, astro-particles and gravitational waves (GW) – multimessenger astrophysics
The matter inside hybrid stars is modelled via a two-model approach: an hadronic phase is connected to a quark phase through a first-order phase transition, i.e., a Maxwell construction is implemented
We study how the quark matter properties a↵ect the existence of stable hybrid stars
Summary
The physics of neutron stars (NS) can be studied by combining astrophysical observations of electromagnetic radiation, astro-particles and gravitational waves (GW) – multimessenger astrophysics. While a not too sti↵ EoS is favored from the upper bond on the tidal deformability, massive pulsars require, on the other hand, a considerably sti↵ EoS for the NS. Such apparent tension might indicate the presence of exotic matter in NS, i.e., non-nucleonic degrees of freedom. The transition, via a first-order phase transition, from hadronic to quark matter at high densities could be an explanation for the existence of low tidal deformabilities for NS masses around 1.4M. Starting from the three-flavor NJL model, we study the e↵ect of several interaction channels in the existence and stability of hybrid stars, and on quark core properties [19–21]
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