Strangelet dwarfs

Alford, Mark; Reddy, Sanjay

doi:10.1088/0954-3899/39/6/065201

Cited by 64 publications

(118 citation statements)

References 54 publications

(132 reference statements)

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“…The screening length has been computed in a different way in [35], finding results analogous to ours. The values of V 0 and of the fitting parameters b and d for the considered models and for two values of M s are reported in Table I.…”

Section: Charge Distributionsupporting

confidence: 74%

Electromagnetic signals from bare strange stars

et al. 2014

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The crystalline color superconducting phase is believed to be the ground state of deconfined quark matter for sufficiently large values of the strange quark mass. This phase has the remarkable property of being more rigid than any known material. It can therefore sustain large shear stresses, supporting torsional oscillations of large amplitude. The torsional oscillations could lead to observable electromagnetic signals if strange stars have a crystalline color superconducting crust. Indeed, considering a simple model of strange star with a bare quark matter surface, it turns out that a positive charge is localized in a narrow shell about ten Fermi thick beneath the star surface. The electrons needed to neutralize the positive charge of quarks spill in the star exterior forming an electromagnetically bounded atmosphere hundreds of Fermi thick. When a torsional oscillation is excited, for example by a stellar glitch, the positive charge oscillates with typical kHz frequencies, for a crust thickness of about one-tenth of the stellar radius, to hundreds of Hz, for a crust thickness of about nine-tenths of the stellar radius. Higher frequencies, of the order of few GHz, can be reached if the star crust is of the order of few centimeters thick. We estimate the emitted power considering emission by an oscillating magnetic dipole, finding that it can be quite large, of the order of 10 45 erg/s for a thin crust. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. The radiated photons will be in part absorbed by the electronic atmosphere, but a sizable fraction of them should be emitted by the star.

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Section: Charge Distributionsupporting

confidence: 74%

Electromagnetic signals from bare strange stars

et al. 2014

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“…In this article we thus utilize a Maxwell construction due to the above mentioned reasons. In refs [20][21][22] the QM EoS was parametrized a relatively simple form (see eq. 11) and the transition from HM to QM can be constructed without any constraints concerning the chemical potential.…”

Section: A Construction Of the Phase Transitionmentioning

confidence: 99%

“…In this article we study various EoS and their solutions within the TOV equations using a Maxwell construction. A stable hybrid star configuration with p c ≥ p t is given, if the mass of the star continues to increase after the quark matter core appears [20][21][22]. As soon as the mass decreases with larger central pressures, the configurations become unstable.…”

Section: Introductionmentioning

confidence: 99%

“…The works of Alford et. al [20][21][22] confirmed that a stable connected hybrid star branch emerges from the hadronic branch if the energy density discontinuity is less than a critical value. They used a constant speed of sound parametrization within the fields correlator method for the QM EoS to provide a general framework for empirical testing and comparison.…”

Section: Introductionmentioning

confidence: 99%

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Stable hybrid stars within a SU(3) quark-meson-model

2016

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The inner regions of the most massive compact stellar objects might be occupied by a phase of quarks. Since the observations of the massive pulsars PSR J1614-2230 and of PSR J0348+0432 with about two solar masses, the equations of state constructing relativistic stellar models have to be constrained respecting these new limits. We discuss stable hybrid stars, i.e. compact objects with an outer layer composed of nuclear matter and with a core consisting of quark matter (QM). For the outer nuclear layer we utilize a density dependent nuclear equation of state and we use a chiral SU(3) Quark-Meson model with a vacuum energy pressure to describe the objects core. The appearance of a disconnected mass-radius branch emerging from the hybrid star branch implies the existence of a third familiy of compact stars, so called twin stars. Twin stars did not emerge as the transition pressure has to be relatively small with a large jump in energy density, which could not be satisfied within our approach. This is, among other reasons, due to the fact that the speed of sound in QM has to be relatively high, which can be accomplished by an increase of the repuslive coupling. This increase on the other hand yields too high transition pressures for twins stars to appear.

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“…We thus never have to introduce a momentum cutoff, which would be necessary if we were to compute loops, for instance in an extension to nonzero temperatures, which has been done within the two-particle irreducible formalism for a single superfluid [32]. Our Lagrangian is very similar to the Ginzburg-Landau model usually considered for superfluid nuclear matter in the core of a neutron star, where the two fields correspond to the Cooper pair condensates of neutrons and protons [33][34][35], for approaches on a more microscopic level, see for instance Refs. [36][37][38].…”

Section: Microscopic Model and Elementary Excitationsmentioning

confidence: 99%

Instabilities in relativistic two-component (super)fluids

2016

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We study two-fluid systems with nonzero fluid velocities and compute their sound modes, which indicate various instabilities. For the case of two zero-temperature superfluids we employ a microscopic field-theoretical model of two coupled bosonic fields, including an entrainment coupling and a non-entrainment coupling. We analyse the onset of the various instabilities systematically and point out that the dynamical two-stream instability can only occur beyond Landau's critical velocity, i.e., in an already energetically unstable regime. A qualitative difference is found for the case of two normal fluids, where certain transverse modes suffer a two-stream instability in an energetically stable regime if there is entrainment between the fluids. Since we work in a fully relativistic setup, our results are very general and of potential relevance for (super)fluids in neutron stars and, in the non-relativistic limit of our results, in the laboratory.

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Strangelet dwarfs

Cited by 64 publications

References 54 publications

Electromagnetic signals from bare strange stars

Electromagnetic signals from bare strange stars

Stable hybrid stars within a SU(3) quark-meson-model

Instabilities in relativistic two-component (super)fluids

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