Shear viscosity in neutron star cores

Shternin, P. S.; Yakovlev, D. G.

doi:10.1103/physrevd.78.063006

Cited by 116 publications

(269 citation statements)

References 36 publications

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“…Therefore, in the analysis of the r-mode instability in nonsuperfluid stars, it has been usual to take η = η n , using for η n the one calculated by Flowers and Itoth [86,87], and fitted by Cutler and Lindblom [88] in the simple form where ρ 15 and T 9 mean that the density and temperature are given in units of 10 15 g cm −3 and 10 9 K, respectively. Nevertheless, recently, Shternin and Yakovlev [89] have shown that the main contribution to the shear viscosity at the temperatures relevant for the spin-down evolution of neutron stars comes from electron scattering when Landau damping is taken into account in the collision of charged particles mediated by the exchange of transverse plasmons. This electron contribution can be written as [18,89] η e = 4 × 10…”

Section: Bulk and Shear Viscositiesmentioning

confidence: 99%

Nuclear symmetry energy and ther-mode instability of neutron stars

Vidaña

2012

Phys. Rev. C

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We analyze the role of the symmetry energy slope parameter L on the r-mode instability of neutron stars. Our study is performed using both microscopic and phenomenological approaches of the nuclear equation of state. The microscopic ones include the Brueckner-Hartree-Fock approximation, the well known variational equation of state of Akmal, Pandharipande and Ravenhall, and a parametrization of recent Auxiliary Field Diffusion Monte Carlo calculations. For the phenomenological approaches, we use several Skyrme forces and relativisic mean field models. Our results show that the r-mode instability region is smaller for those models which give larger values of L. The reason is that both bulk (ξ ) and shear (η) viscosities increase with L and, therefore, the damping of the mode is more efficient for the models with larger L. We show also that the dependence of both viscosities on L can be described at each density by simple power-laws of the type ξ = A ξ L B ξ and η = A η L B η . Using the measured spin frequency and the estimated core temperature of the pulsar in the low-mass X-ray binary 4U 1608-52, we conclude that observational data seem to favor values of L larger than ∼ 50 MeV if this object is assumed to be outside the instability region, its radius is in the range 11.5 − 12(11.5 − 13) km, and its mass 1.4M ⊙ (2M ⊙ ). Outside this range it is not possible to draw any conclusion on L from this pulsar.

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Section: Bulk and Shear Viscositiesmentioning

confidence: 99%

Nuclear symmetry energy and ther-mode instability of neutron stars

Vidaña

2012

Phys. Rev. C

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“…This result is valid over the density range 10 14 < ρ < 4 × 10 14 . More recent calculations for the electron viscosity have been performed by Andersson et al (2005) and Shternin & Yakovlev (2008) accounting for superfluidity of proton matter. The former finds results broadly consistent with Equation (53), while the latter accounts for transverse Landau damping in charged particle collisions neglected in previous studies, an effect that results in viscosities a factor of three smaller than that predicted by Equation (53).…”

Section: Application To Neutron Starsmentioning

confidence: 99%

Short-Period Pulsar Oscillations Following a Glitch

Eysden

2014

ApJ

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Following a glitch, the crust and magnetized plasma in the outer core of a neutron star are believed to rapidly establish a state of co-rotation within a few seconds by process analogous to classical Ekman pumping. However, in ideal magnetohydrodynamics, a final state of co-rotation is inconsistent with conservation of energy of the system. We demonstrate that, after the Ekman-like spin up is completed, magneto-inertial waves continue to propagate throughout the star, exciting torsional oscillations in the crust and plasma. The crust oscillation is irregular and quasi-periodic, with a dominant frequency of the order of seconds. Crust oscillations commence after an Alfvén crossing time, approximately half a minute at the magnetic pole, and are subsequently damped by the electron viscosity over approximately an hour. In rapidly rotating stars, the magneto-inertial spectrum in the core approaches a continuum, and crust oscillations are damped by resonant absorption analogous to quasi-periodic oscillations in magnetars. The oscillations predicted are unlikely to be observed in timing data from existing radio telescopes, but may be visible to next generation telescope arrays.

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“…Due to the multi-fluid nature of the superfluid/superconducting mixture, there are not simply two components coupled by a single resistive force. We could imagine a variety of ways for the components to interact with each other ranging from electron scattering (Sauls, Stein & Serene 1982;Alpar, Langer & Sauls 1984;Andersson, Sidery & Comer 2006) and vortexfluxtube interactions (Ruderman, Zhu & Chen 1998;Jahan-Miri 2000;Link 2003) to shear or bulk viscosity (Andersson, Comer & Glampedakis 2005;Shternin & Yakovlev 2008;Manuel, Tarrus & Tolos 2013). Choosing a more pedagogical approach to our problem, we pick one specific mechanism, determine how it affects the electrons on mesoscopic scales and translate this into a macroscopic picture.…”

Section: The Coupling Force: 'Standard' Resistivitymentioning

confidence: 99%

Magnetic field evolution in superconducting neutron stars

Graber

Andersson

Glampedakis

et al. 2015

Mon. Not. R. Astron. Soc.

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The presence of superconducting and superfluid components in the core of mature neutron stars calls for the rethinking of a number of key magnetohydrodynamical notions like resistivity, the induction equation, magnetic energy and flux-freezing. Using a multi-fluid magnetohydrodynamics formalism, we investigate how the magnetic field evolution is modified when neutron star matter is composed of superfluid neutrons, type-II superconducting protons and relativistic electrons. As an application of this framework, we derive an induction equation where the resistive coupling originates from the mutual friction between the electrons and the vortex/fluxtube arrays of the neutron and proton condensates. The resulting induction equation allows the identification of two timescales that are significantly different from those of standard magnetohydrodynamics. The astrophysical implications of these results are briefly discussed.

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Shear viscosity in neutron star cores

Cited by 116 publications

References 36 publications

Nuclear symmetry energy and ther-mode instability of neutron stars

Nuclear symmetry energy and ther-mode instability of neutron stars

Short-Period Pulsar Oscillations Following a Glitch

Magnetic field evolution in superconducting neutron stars

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