Stratification, superfluidity and magnetar QPOs

Passamonti, Andrea; Lander, S. K.

doi:10.1093/mnras/sts372

Cited by 38 publications

(49 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Taking into account effects associated with superfluidity may also be the answer. Superfluidity can move the continua such that damping is reduced (van Hoven & Levin 2008;Andersson et al 2009;Passamonti & Lander 2013) and may result in resonances between crust and core that could prolong mode lifetimes (Gabler et al 2013;Passamonti & Lander 2013). In fact, in their axisymmetric model Gabler et al (2013) found an oscillation at ∼600 Hz; however, this work did not demonstrate numerical convergence of this result.…”

Section: Introductionmentioning

confidence: 69%

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

Watts

Levin

2014

ApJ

View full text Add to dashboard Cite

Quasi-periodic oscillations (QPOs) detected in the 2004 giant flare from SGR 1806-20 are often interpreted as global magneto-elastic oscillations of the neutron star. There is, however, a large discrepancy between theoretical models, which predict that the highest frequency oscillations should die out rapidly, and the observations, which suggested that the highest-frequency signals persisted for ∼100 s in X-ray data from two different spacecraft. This discrepancy is particularly important for the high-frequency QPO at ∼625 Hz. However, previous analyses did not systematically test whether the signal could also be present in much shorter data segments, more consistent with the theoretical predictions. Here, we test for the presence of the high-frequency QPO at 625 Hz in data from both the Rossi X-ray Timing Explorer (RXTE) and the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) systematically both in individual rotational cycles of the neutron star, as well as averaged over multiple successive rotational cycles at the same phase. We find that the QPO in the RXTE data is consistent with being only present in a single cycle, for a short duration of ∼0.5 s, whereas the RHESSI data are as consistent with a short-lived signal that appears and disappears as with a long-lived QPO. Taken together, this data provides evidence for strong magnetic interaction between the crust and the core.

show abstract

Section: Introductionmentioning

confidence: 69%

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

Watts

Levin

2014

ApJ

View full text Add to dashboard Cite

show abstract

“…However, to us it seems hard to explain why only these particular overtones should be excited and not many more. A possible explanation was first presented in Gabler et al (2013b) and was confirmed by Passamonti & Lander (2013). Both groups find a preferential excitation of only a few particular high Alfvén overtones in the core: Let the crust be initially perturbed by a deformation with spatial structure corresponding to the eigenfunction of a crustal shear mode (as may happen during a giant flare).…”

Section: High-frequency Qposmentioning

confidence: 85%

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

View full text Add to dashboard Cite

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.

show abstract

“…(Braithwaite and Spruit 2004a;Braithwaite and Nordlund 2006b;Akgün et al 2013;Ciolfi and Rezzolla 2013;Gourgouliatos et al 2013;Lander and Jones 2012;Mitchell et al 2013;Passamonti and Lander 2013). A comprehensive review lies outside the scope of this chapter; we simply mention a few highlights.…”

Section: Generation Physicsmentioning

confidence: 99%

Magnetic Field Generation in Stars

2015

View full text Add to dashboard Cite

Enormous progress has been made on observing stellar magnetism in stars from the main sequence through to compact objects. Recent data have thrown into sharper relief the vexed question of the origin of stellar magnetic fields, which remains one of the main unanswered questions in astrophysics. In this chapter we review recent work in this area of research. In particular, we look at the fossil field hypothesis which links magnetism in compact stars to magnetism in main sequence and pre-main sequence stars and we consider why its feasibility has now been questioned particularly in the context of highly magnetic white dwarfs. We also review the fossil versus dynamo debate in the context of neutron stars and the roles played by key physical processes such as buoyancy, helicity, and superfluid turbulence,in the generation and stability of neutron star fields. Independent information on the internal magnetic field of neutron stars will come from future gravitational wave detections. Thus we maybe at the dawn of a new era of exciting discoveries in compact star magnetism driven by the opening of a new, non-electromagnetic observational window. We also review recent advances in the theory and computation of magnetohydrodynamic turbulence as it applies to stellar magnetism and dynamo theory. These advances offer insight into the action of stellar dynamos as well as processes whichcontrol the diffusive magnetic flux transport in stars.Comment: 41 pages, 7 figures. Invited review chapter on on magnetic field generation in stars to appear in Space Science Reviews, Springe

show abstract

Stratification, superfluidity and magnetar QPOs

Cited by 38 publications

References 44 publications

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

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

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

Magnetic Field Generation in Stars

Contact Info

Product

Resources

About