Role of strangeness in hybrid stars and possible observables

Dexheimer, V.; Negreiros, Rodrigo; Schramm, Stefan

doi:10.1103/physrevc.91.055808

Cited by 49 publications

(46 citation statements)

References 77 publications

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“…As it is not clear that a first-order phase hadron-toquark transition at finite baryon density is demanded by fundamental considerations, crossover or second-order transitions have also been explored recently; see, e.g., Refs. [65,69,70]. As details of results ensuing from the model of Ref.…”

Section: Crossover Transitionsmentioning

confidence: 98%

Treating quarks within neutron stars

et al. 2019

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Neutron star interiors provide the opportunity to probe properties of cold dense matter in the QCD phase diagram. Utilizing models of dense matter in accord with nuclear systematics at nuclear densities, we investigate the compatibility of deconfined quark cores with current observational constraints on the maximum mass and tidal deformability of neutron stars. We explore various methods of implementing the hadron-to-quark phase transition, specifically, first-order transitions with sharp (Maxwell construction) and soft (Gibbs construction) interfaces, and smooth crossover transitions. We find that within the models we apply, hadronic matter has to be stiff for a first-order phase transition and soft for a crossover transition. In both scenarios and for the equations of state we employed, quarks appear at the center of pre-merger neutron stars in the mass range ≈ 1.0 − 1.6 M , with a squared speed of sound c 2 QM 0.4 characteristic of strong repulsive interactions required to support the recently discovered neutron star masses ≥ 2 M . We also identify equations of state and phase transition scenarios that are consistent with the bounds placed on tidal deformations of neutron stars in the recent binary merger event GW170817. We emphasize that distinguishing hybrid stars with quark cores from normal hadronic stars is very difficult from the knowledge of masses and radii alone, unless drastic sharp transitions induce distinctive disconnected hybrid branches in the mass-radius relation.

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Section: Crossover Transitionsmentioning

confidence: 98%

Treating quarks within neutron stars

et al. 2019

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“…In several recent papers [18][19][20][21][22][23][24], it has been shown that they may contain significant fractions of quark-hybrid matter in their centers, despite the relatively stiff nuclear equation of state (EoS) that is required to achieve such high masses. The radii of these neutron stars would be between 13 and 14 km, depending on the nuclear EoS [18,19], increasing to respectively 13.5 and 14.5 km for lighter neutron stars with canonical masses of around 1.4 M ⊙ .…”

Section: Introductionmentioning

confidence: 99%

Thermal evolution of hybrid stars within the framework of a nonlocal Nambu–Jona-Lasinio model

et al. 2015

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We study the thermal evolution of neutron stars containing deconfined quark matter in their core. Such objects are generally referred to as quark-hybrid stars. The confined hadronic matter in their core is described in the framework of non-linear relativistic nuclear field theory. For the quark phase we use a non-local extension of the SU(3) Nambu Jona-Lasinio model with vector interactions. The Gibbs condition is used to model phase equilibrium between confined hadronic matter and deconfined quark matter. Our study indicates that high-mass neutron stars may contain between 35 and 40% deconfined quark-hybrid matter in their cores. Neutron stars with canonical masses of around 1.4 M⊙ would not contain deconfined quark matter. The central proton fractions of the stars are found to be high, enabling them to cool rapidly. Very good agreement with the temperature evolution established for the neutron star in Cassiopeia A (Cas A) is obtained for one of our models (based on the popular NL3 nuclear parametrization), if the protons in the core of our stellar models are strongly paired, the repulsion among the quarks is mildly repulsive, and the mass of Cas A has a canonical value of 1.4 M⊙.

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“…As was shown in [28], depending on the strength of the vector interaction of the strange quark, a first-order phase transition can occur. Calculating the massradius diagram of compact stars for the corresponding equation of state, this effect can be seen as a sudden cut-off of stable stellar solutions.…”

Section: Pos(icpaqgp2015)009mentioning

confidence: 67%

“…For specific choices of the relative coupling of strange quarks and non-strange quarks to the respective vector fields ξ = g sφ /g qω twin solutions of strangeness-enriched hybrid stars occur with masses around 1.7 solar masses and radii between 9 and 10 km with non-strange counterparts with large masses and larger radii. Thus, within this model there is the possibility of a class of stars with very distinct radii and a changed composition that might lead to observable effects, for instance in their cooling behaviour [28]. …”

Section: Pos(icpaqgp2015)009mentioning

confidence: 99%