INTERMITTENCY AND LIFETIME OF THE 625 Hz QUASI-PERIODIC OSCILLATION IN THE 2004 HYPERFLARE FROM THE MAGNETAR SGR 1806-20 AS EVIDENCE FOR MAGNETIC COUPLING BETWEEN THE CRUST AND THE CORE

Huppenkothen, Daniela; Watts, Anna L.; Levin, Y.

doi:10.1088/0004-637x/793/2/129

Cited by 30 publications

(38 citation statements)

References 36 publications

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“…4 and thus comparable to what was found by van Hoven & Levin (2012). Such a short damping time can not account for the observation of the 625 Hz QPO in SGR 1806-20, as its damping time derived from observations is longer than at least about 500 ms (Huppenkothen et al 2014b). On the other hand, the high-frequency magneto-elastic QPO close to the pole survives for much longer times.…”

Section: High-frequency Qpossupporting

confidence: 44%

Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations

Gabler

Cerdá–Durán

Stergioulas

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We discuss torsional oscillations of highly magnetised neutron stars (magnetars) using twodimensional, magneto-elastic-hydrodynamical simulations. Our model is able to explain both the low-and high-frequency quasi-periodic oscillations (QPOs) observed in magnetars. The analysis of these oscillations provides constraints on the breakout magnetic-field strength, on the fundamental QPO frequency, and on the frequency of a particularly excited overtone. More importantly, we show how to use this information to generically constraint properties of high-density matter in neutron stars, employing Bayesian analysis. In spite of current uncertainties and computational approximations, our model-dependent Bayesian posterior estimates for SGR 1806-20 yield a magnetic-field strengthB ∼ 2.1 +1.3 −1.0 × 10 15 G and a crust thickness of ∆r = 1.6 +0.7 −0.6 km, which are both in remarkable agreement with observational and theoretical expectations, respectively (1-σ error bars are indicated). Our posteriors also favour the presence of a superfluid phase in the core, a relatively low stellar compactness, M/R < 0.19, indicating a relatively stiff equation of state and/or low mass neutron star, and high shear speeds at the base of the crust, c s > 1.4 × 10 8 cm/s. Although the procedure laid out here still has large uncertainties, these constraints could become tighter when additional observations become available.

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Section: High-frequency Qpossupporting

confidence: 44%

Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations

Gabler

Cerdá–Durán

Stergioulas

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…In either internally or externally-triggered scenarios, a scaling of the square amplitude of the crust/field oscillations (in the elastic regime) may be regarded as a proxy for the event's energy release (see below and §2.3). Additionally, since the core-crust coupling is suggested by the damping of QPOs within < ∼ 0.2 − 2 s in short bursts (Huppenkothen et al 2014b;Miller et al 2019), such damping may limit the duration of FRB recurrence clusters (that is, the span of short-waiting-time events, as exhibited in FRB 121102) for individual triggering events. Multiple field dislocation episodes then correspond to similar FRB repetition statistics as magnetar short bursts.…”

Section: The Model: Constraints On Neutron Star Period and Surface Mamentioning

confidence: 99%

The Fast Radio Burst Luminosity Function and Death Line in the Low-twist Magnetar Model

Wadiasingh

Beniamini

Timokhin

et al. 2020

ApJ

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We explore the burst energy distribution of fast radio bursts (FRBs) in the low-twist magnetar model of Wadiasingh & Timokhin (2019). Motivated by the power-law fluence distributions of FRB 121102, we propose an elementary model for the FRB luminosity function of individual repeaters with an inversion protocol which directly relates the power-law distribution index of magnetar short burst fluences to that for FRBs. The protocol indicates the FRB energy scales virtually linearly with crust/field dislocation amplitude, if magnetar short bursts prevail in the magnetoelastic regime. Charge starvation in the magnetosphere during bursts (required in WT19) for individual repeaters implies the predicted burst fluence distribution is narrow, < ∼ 3 decades for yielding strains and oscillation frequencies feasible in magnetar crusts. Requiring magnetic confinement and charge starvation, we obtain a death line for FRBs which segregates magnetars from the normal pulsar population, suggesting only the former will host FRBs. We convolve the burst energy distribution for individual magnetars to define the distribution of luminosities in evolved magnetar populations. The broken power-law luminosity function's low energy character depends on the population model, while the high energy index traces that of individual repeaters. Independent of the evolved population, the broken power-law isotropic-equivalent energy/luminosity function peaks at ∼ 10 38 − 10 40 erg with a sharp low-energy cutoff at < ∼ 10 37 erg. Lastly, we consider the local fluence distribution of FRBs, and find that it can constrain the subset of FRB-producing magnetar progenitors. Our model suggests that improvements in sensitivity may reveal flattening of the global FRB fluence distribution and saturation in FRB rates. 1/7 c and ε CR,pp ∝ ρ 1/2 c . There also exist regimes between B ∼ 10 13 − 10 14 G where the splitting length may be shorter than the pair length, owing to the dependence of splitting amplitude integrals M σ on B (for details, see Hu et al. 2019). A more complete study of pair cascades with splitting for FRB models is deferred to the future.

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“…Observations of quasi-periodic oscillations (QPOs) in the tails of two giant flares Strohmayer & Watts 2005) has engendered excitement about the potential new field of neutron star asteroseismology. In particular, the interpretation of QPOs as stellar magneto-elastic oscillations provide enticing potential to infer neutron star structural parameters (see Gabler et al 2013Gabler et al , 2014Huppenkothen, Watts, & Levin 2014c, and references therein).…”

Section: Magnetar Flaresmentioning

confidence: 99%

Gravitational Waves from Neutron Stars: A Review

Lasky

2015

Publ. Astron. Soc. Aust.

171

109

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Neutron stars are excellent emitters of gravitational waves. Squeezing matter beyond nuclear densities invites exotic physical processes, many of which violently transfer large amounts of mass at relativistic velocities, disrupting spacetime and generating copious quantities of gravitational radiation. I review mechanisms for generating gravitational waves with neutron stars. This includes gravitational waves from radio and millisecond pulsars, magnetars, accreting systems, and newly born neutron stars, with mechanisms including magnetic and thermoelastic deformations, various stellar oscillation modes, and core superfluid turbulence. I also focus on what physics can be learnt from a gravitational wave detection, and where additional research is required to fully understand the dominant physical processes at play.

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INTERMITTENCY AND LIFETIME OF THE 625 Hz QUASI-PERIODIC OSCILLATION IN THE 2004 HYPERFLARE FROM THE MAGNETAR SGR 1806-20 AS EVIDENCE FOR MAGNETIC COUPLING BETWEEN THE CRUST AND THE CORE

Cited by 30 publications

References 36 publications

Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations

Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations

The Fast Radio Burst Luminosity Function and Death Line in the Low-twist Magnetar Model

Gravitational Waves from Neutron Stars: A Review

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