Continuous-wave gravitational radiation from pulsar glitch recovery

Bennett, Mark F; Eysden, C. A. van; Melatos, A.

doi:10.1111/j.1365-2966.2010.17416.x

Cited by 53 publications

(98 citation statements)

References 80 publications

(202 reference statements)

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“…During spin up, burst signals are expected in the current quadrupole channel, as quantized neutron vortices reorganize spatially within the superfluid interior of the star , and in the mass quadrupole channel, as the energy released by the glitch trigger (e.g., a starquake or crust-superfluid coupling) excites acoustic and inertial stellar oscillations: f-, p-, and w-modes (Thorne & Campolattaro 1967;Kokkotas et al 2001;Sedrakian et al 2003), r-modes (Santiago-Prieto et al 2012), and their two-component superfluid counterparts (Sidery et al 2010). After spin up, a decaying, quasimonochromatic, current quadrupole signal is expected, as the superfluid and crust relax to corotation via a combination of Ekman pumping and mutual friction (van Eysden & Melatos 2008;Bennett et al 2010). Calorimetric upper bounds imply that the burst (Andersson & Comer 2001;Abadie et al 2011) and quasimonochromatic (Prix & Giampanis 2011) signals are marginally detectable by next-generation interferometers like the Einstein Telescope given efficient energy conversion.…”

Section: Introductionmentioning

confidence: 99%

“…Calorimetric upper bounds imply that the burst (Andersson & Comer 2001;Abadie et al 2011) and quasimonochromatic (Prix & Giampanis 2011) signals are marginally detectable by next-generation interferometers like the Einstein Telescope given efficient energy conversion. A detection, albeit challenging, would enable new, precise measurements of the compressibility, viscosity, and state of superfluidity of bulk nuclear matter (Andersson & Comer 2001;Kokkotas et al 2001;Bennett et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Persistent Gravitational Radiation From Glitching Pulsars

Melatos

Douglass

Simula

2015

ApJ

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Quantum mechanical simulations of neutron star rotational glitches, triggered by vortex avalanches in the superfluid stellar interior, reveal that vortices pin nonaxisymmetrically to the crust during the intervals between glitches. Hence a glitching neutron star emits a persistent current quadrupole gravitational wave signal at the star's rotation frequency, whose interglitch amplitude is constant and determined by the avalanche history since birth. The signal can be detected in principle by coherent searches planned for the Laser Interferometer Gravitational Wave Observatory (LIGO), whether or not a glitch occurs during the observation, if the power-law distribution of glitch sizes extends up to D 10 ( ) ( 10 rad s ) ( 1 kpc)in the targeted object, where max DW and f D are the largest angular velocity jump and avalanche opening angle, respectively, to have occurred in a glitch since birth, Ω is the angular velocity at present, η is the crustal fraction of the moment of inertia, and D is the distance from the Earth. A major caveat concerning detectability is whether the nonaxisymmetries observed in existing simulations with 10 3  vortices extrapolate to realistic neutron stars with 10 15  vortices. The arguments for and against extrapolation are discussed critically in the context of avalanche dynamics in self-organized critical systems, but the issue cannot be resolved without larger simulations and tighter observational limits on max h f D DW from future LIGO (non)detections and radio timing campaigns.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Persistent Gravitational Radiation From Glitching Pulsars

Melatos

Douglass

Simula

2015

ApJ

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“…The continuous-wave signal is generated by residual non-axisymmetries in the superfluid velocity field, some parts of which are erased on the post-glitch recovery time-scale. Flow non-axisymmetries arise from Ekman circulation [207,208] and/or oscillatory vortex structures at high Reynolds number, e.g. Taylor-Gortler modes [28,209].…”

Section: Gravitational Wavesmentioning

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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“…If Ekman pumping proceeds nonaxisymmetrically-a likely scenario, as the Reynolds number typically exceeds ∼10 9 , well above the threshold for nonaxisymmetric instabilities like Taylor-Gortler vortices-the post-glitch recovery is accompanied by emission of a quasimonochromatic gravitational wave signal [2], which lasts for days to weeks and can be detected in principle by pipelines developed for "long transients". A powerful multimessenger experiment is therefore possible in principle: the radio and gravitational wave data (dual polarizations) can be combined to infer the compressibility, viscosity, and stratification length-scale of bulk nuclear matter [2], strengthening the constraints on the existence of exotic (e.g., color-flavor-locked) phases already deduced from radio data [1]. Predictions of the signal-to-noise ratio are presented in detail in Figure 3 of [2] and exceed ∼3 for Advanced LIGO across a range of plausible compressibilities and viscosities.…”

Section: Andrew Melatosmentioning

confidence: 99%

“…A powerful multimessenger experiment is therefore possible in principle: the radio and gravitational wave data (dual polarizations) can be combined to infer the compressibility, viscosity, and stratification length-scale of bulk nuclear matter [2], strengthening the constraints on the existence of exotic (e.g., color-flavor-locked) phases already deduced from radio data [1]. Predictions of the signal-to-noise ratio are presented in detail in Figure 3 of [2] and exceed ∼3 for Advanced LIGO across a range of plausible compressibilities and viscosities.…”

Section: Andrew Melatosmentioning

confidence: 99%