Kelvin-Helmholtz instability and circulation transfer at an isotropic-anisotropic superfluid interface in a neutron star

Mastrano, Alpha; Melatos, A.

doi:10.1111/j.1365-2966.2005.09219.x

Cited by 44 publications

(61 citation statements)

References 36 publications

(129 reference statements)

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“…When the relative velocity between the two phases exceeds a critical value, the penetration of quantized vortices across the interface was detected by counting the number of vortices by NMR before and after the instability 1 . The Kelvin-Helmholtz instability in superfluid systems has been discussed on different kinds of interfaces, such as normal-superfluid interfaces [110,160], nuclear-nuclear superfluid interfaces [161], and superfluid-superfluid inter-face in atomic two-component BECs [162].…”

Section: Hydrodynamic Instabilities In Superfluid Systemsmentioning

confidence: 99%

Quantum hydrodynamics

Tsubota¹,

Kobayashi²,

Takeuchi³

2013

Physics Reports

157

181

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Quantum hydrodynamics in superfluid helium and atomic Bose-Einstein condensates (BECs) has been recently one of the most important topics in low temperature physics. In these systems, a macroscopic wave function (order parameter) appears because of Bose-Einstein condensation, which creates quantized vortices. Turbulence consisting of quantized vortices is called quantum turbulence (QT). The study of quantized vortices and QT has increased in intensity for two reasons. The first is that recent studies of QT are considerably advanced over older studies, which were chiefly limited to thermal counterflow in 4 He, which has no analogue with classical traditional turbulence, whereas new studies on QT are focused on a comparison between QT and classical turbulence. The second reason is the realization of atomic BECs in 1995, for which modern optical techniques enable the direct control and visualization of the condensate and can even change the interaction; such direct control is impossible in other quantum condensates like superfluid helium and superconductors. Our group has made many important theoretical and numerical contributions to the field of quantum hydrodynamics of both superfluid helium and atomic BECs. In this article, we review some of the important topics in detail. The topics of quantum hydrodynamics are diverse, so we have not attempted to cover all these topics in this article. We also ensure that the scope of this article does not overlap with our recent review article (arXiv:1004.5458), "Quantized vortices in superfluid helium and atomic Bose-Einstein condensates", and other review articles.

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Section: Hydrodynamic Instabilities In Superfluid Systemsmentioning

confidence: 99%

Quantum hydrodynamics

Tsubota¹,

Kobayashi²,

Takeuchi³

2013

Physics Reports

157

181

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“…Mastrano and Melatos [181] suggested that a Kelvin-Helmholtz instability at the interface between the 1 S 0 and 3 P 2 superfluids in the star may trigger the glitch, complementing the bulk two-stream instability discussed above.…”

Section: Hydrodynamical Instabilitesmentioning

confidence: 99%

Models of pulsar glitches

Haskell

Melatos

2015

Int. J. Mod. Phys. D

318

304

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Radio pulsars provide us with some of the most stable clocks in the universe. Nevertheless several pulsars exhibit sudden spin-up events, known as glitches. More than forty years after their first discovery, the exact origin of these phenomena is still open to debate. It is generally thought that they an observational manifestation of a superfluid component in the stellar interior and provide an insight into the dynamics of matter at extreme densities. In recent years there have been several advances on both the theoretical and observational side, that have provided significant steps forward in our understanding of neutron star interior dynamics and possible glitch mechanisms. In this article we review the main glitch models that have been proposed and discuss our understanding, in the light of current observations.Radio pulsars are thought to be rotating magnetised neutron stars (NS). The huge moment of inertia (of the order of 10 45 g cm 2 ) leads to exceptionally stable rotation rates and provides us with some of the most precise clocks in the universe. The best timed millisecond pulsars are stable to a precision which rivals that of atomic clocks [1]. Nevertheless radio pulsars exhibit several timing irregularities, the most striking of which are the so-called glitches. While most objects are observed to steadily spin-down due to the emission of electromagnetic and, possibly, gravitational waves, many pulsars show sudden increases in their spin, in some cases followed by an increase in their spin-down rate, i.e. glitches. Most pulsars also show slower, long-term, stochastic deviations from a regular spin-down law, that are generally classed as 'timing noise' and are not the main focus of this review article.Soon after the discovery of the first glitches in the Vela [2,3] and Crab [4,5] pulsars in 1969, several mechanisms were suggested to explain these phenomena. Although some initial suggestions featured external mechanisms, such as plasma explosions in the magnetosphere [6] or planets around the pulsar [7], the lack of radiative and pulse profile changes associated with these events was taken as evidence for an internal origin. The situation is different for rotating radio transients (RRATs) and magnetars, which are now known to glitch and do exhibit, amongst other peculiar traits, radiative changes associated with these events [8][9][10][11]. Magnetospheric activity is likely to play a role in these objects, as we discuss below.There are two main internal glitch mechanisms that have been examined in the literature. The first set of models relies on the fact that the outer layers of a neutron star form a crystalline crust that can support stress. As the NS spins down, the liquid core adjusts its shape to the rotation rate, while the solid crust maintains the shape appropriate for the previous, higher, spin rate. This leads to an increasing amount of strain building up in the crust, which is eventually released in the form of a star quake. The quake causes a sudden rearrangement of the moment of inertia and...

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“…Here, for simplicity, we assume that the isotropic 1 S 0 phase fills the entire outer core. The 3 P 2 phase is anisotropic: gradients in the orientation (texture) of the pair angular momenta drive counterflows between the viscous and inviscid components of the superfluid (Vollhard & Wölfle 2002;Mastrano & Melatos 2005), introducing complications (e.g., boundary conditions at the 1 S 0 -3 P 2 interface) that lie outside the scope of this paper. 4 The outer core contains charged species, particularly protons and electrons, which are incorporated into the viscous component of the superfluid in our simulations.…”

Section: Idealized Hydrodynamic Model Of the Outer Core Of A Neutron mentioning

confidence: 99%

Global Three‐dimensional Flow of a Neutron Superfluid in a Spherical Shell in a Neutron Star

Peralta¹,

Melatos²,

Giacobello³

et al. 2005

ApJ

Self Cite

139

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We integrate for the first time the hydrodynamic Hall-Vinen-Bekarevich-Khalatnikov equations of motion of a 1 S 0 -paired neutron superfluid in a rotating spherical shell, using a pseudo-spectral collocation algorithm coupled with a time-split fractional scheme. Numerical instabilities are smoothed by spectral filtering. Three numerical experiments are conducted, with the following results. (1) When the inner and outer spheres are put into steady differential rotation, the viscous torque exerted on the spheres oscillates quasi-periodically and persistently (after an initial transient). The fractional oscillation amplitude ($10 À2 ) increases with the angular shear and decreases with the gap width.(2) When the outer sphere is accelerated impulsively after an interval of steady differential rotation, the torque increases suddenly, relaxes exponentially, then oscillates persistently as in (1). The relaxation timescale is determined principally by the angular velocity jump, whereas the oscillation amplitude is determined principally by the gap width. (3) When the mutual friction force changes suddenly from Hall-Vinen to Gorter-Mellink form, as happens when a rectilinear array of quantized Feynman-Onsager vortices is destabilized by a counterflow to form a reconnecting vortex tangle, the relaxation timescale is reduced by a factor of $3 compared to (2), and the system reaches a stationary state in which the torque oscillates with fractional amplitude $10 À3 about a constant mean value. Preliminary scalings are computed for observable quantities such as angular velocity and acceleration as functions of the Reynolds number, angular shear, and gap width. The results are applied to the timing irregularities (e.g., glitches and timing noise) observed in radio pulsars.

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Kelvin-Helmholtz instability and circulation transfer at an isotropic-anisotropic superfluid interface in a neutron star

Cited by 44 publications

References 36 publications

Quantum hydrodynamics

Quantum hydrodynamics

Models of pulsar glitches

Global Three‐dimensional Flow of a Neutron Superfluid in a Spherical Shell in a Neutron Star

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