Abstract:We investigate the properties of mixed stars formed by hadronic and quark matter in β-equilibrium described by appropriate equations of state (EOS) in the framework of relativistic mean-field theory. We use the non-linear Walecka model for the hadron matter and the MIT Bag and the Nambu-Jona-Lasinio models for the quark matter. The calculations were performed for T = 0 and for finite temperatures in order to describe neutron and proto-neutron stars. The star properties are discussed. Both the Bag model and the… Show more
“…Actually, the radius can increase up to huge values if densities as low as 10 −15 fm −3 are considered. In order to plot this figure for the hadronic and hybrid stars, we choose the EOS derived in , 2004c, where the hybrid stars were obtained by the enforcement of Gibbs criterion for phase coexistence. In this case, the EOS is smooth and no discontinuities are present.…”
Section: Resultsmentioning
confidence: 99%
“…Strange matter is composed of deconfined quarks, including up, down, and strange quarks, plus the leptons necessary to ensure charge neutrality (Bodmer 1971;Witten 1984). This possibility arises because at the high densities present in the interior of neutron stars, a phase transition from hadronic to quark phase is possible (Glendenning 2000;Menezes & Providência 2003, 2004c. Approximately one-third of the quarks are strange quarks, with the exact fraction depending on the model used to describe the quark phase.…”
Section: Introductionmentioning
confidence: 99%
“…In hybrid stars low-density regions are composed of hadronic matter, but in high-density regions a deconfinement of the quarks from the hadrons occurs, leading to a quark phase. Many different EOS have been built, including EOS for the phase immediately after the formation of the neutron star when the neutrinos are still trapped (Panda et al 2004a; and for the subsequent (deleptonized) phase after the neutrinos escape (Menezes & Providência 2003, 2004cPanda et al 2004b).…”
Motivated by recent suggestions that strange stars can be responsible for glitches and other observational features of pulsars, we review some possible equations of state and their implications for models of neutron, hybrid, and strange stars. We consider the MIT bag model and also strange matter in the colourflavour locked phase. The central energy densities for strange stars are higher than the central densities of ordinary neutron stars. Strange stars are bound by the strong force and so can also rotate much faster than neutron stars. These results are only weakly dependent on the model used for the quark matter. If just one of the existing mass-to-radius ratio constraint is valid, most neutron stars equations of state are ruled out, but all the strange stars equations of state presented in this work remain consistent with the constraint.
“…Actually, the radius can increase up to huge values if densities as low as 10 −15 fm −3 are considered. In order to plot this figure for the hadronic and hybrid stars, we choose the EOS derived in , 2004c, where the hybrid stars were obtained by the enforcement of Gibbs criterion for phase coexistence. In this case, the EOS is smooth and no discontinuities are present.…”
Section: Resultsmentioning
confidence: 99%
“…Strange matter is composed of deconfined quarks, including up, down, and strange quarks, plus the leptons necessary to ensure charge neutrality (Bodmer 1971;Witten 1984). This possibility arises because at the high densities present in the interior of neutron stars, a phase transition from hadronic to quark phase is possible (Glendenning 2000;Menezes & Providência 2003, 2004c. Approximately one-third of the quarks are strange quarks, with the exact fraction depending on the model used to describe the quark phase.…”
Section: Introductionmentioning
confidence: 99%
“…In hybrid stars low-density regions are composed of hadronic matter, but in high-density regions a deconfinement of the quarks from the hadrons occurs, leading to a quark phase. Many different EOS have been built, including EOS for the phase immediately after the formation of the neutron star when the neutrinos are still trapped (Panda et al 2004a; and for the subsequent (deleptonized) phase after the neutrinos escape (Menezes & Providência 2003, 2004cPanda et al 2004b).…”
Motivated by recent suggestions that strange stars can be responsible for glitches and other observational features of pulsars, we review some possible equations of state and their implications for models of neutron, hybrid, and strange stars. We consider the MIT bag model and also strange matter in the colourflavour locked phase. The central energy densities for strange stars are higher than the central densities of ordinary neutron stars. Strange stars are bound by the strong force and so can also rotate much faster than neutron stars. These results are only weakly dependent on the model used for the quark matter. If just one of the existing mass-to-radius ratio constraint is valid, most neutron stars equations of state are ruled out, but all the strange stars equations of state presented in this work remain consistent with the constraint.
“…Another well known model is the Nambu-Jona-Lasinio model [16,17] used to investigate quark matter properties in compact stars in Refs. [18,19]. It exhibits chiral symmetry breaking, but the quark confinement is not explicitly included.…”
We investigate general aspects of the mass defects of strange stars in the context of the Field Correlator Method, without magnetic field. The main parameters of the model that enter the corresponding nonperturbative equation of state of the quark gluon plasma are the gluon condensate G 2 and the large distance static QQ potential V 1 .We calculate mass defects of stellar configurations in the central density range 11 < log ρ c < 18. In general, the mass defects are strongly dependent on the model parameters. For a large range of values of G 2 and V 1 , we obtain anomalous mass defects with magnitudes around 10 53 erg , of the same order of the observed energies of gamma-ray bursts and neutrino emissions in SN1987A, and of the theoretically predicted energies of the quark-novae explosions.
“…The current treatments have led to theoretical results which are unable to fully explain the observed phenomena of compact astrophysical objects. Among these treatments, the Nambu-Jona-Lasinio (NJL) model [1,2] and MIT Bag model [3] have been used in the study of compact stars to describe quark matter at nonzero temperature and density [4][5][6]. However, in both the NJL and MIT Bag models, quarks enter in the respective EOS as a free quark gas with Fermi-Dirac distribution.…”
We calculate the strange star properties in the framework of the Field Correlator Method. We find that for the values of the gluon condensate G 2 = 0.006 GeV 4 and G 2 = 0.0068 GeV 4 , which give a critical temperature T c ∼ 170 MeV at µ c = 0, the sequences of strange stars are compatible with some of the semi-empirical massradius relations and data obtained from astrophysical observations.
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