Search results for "Magneto elastic"

showing 3 items of 3 documents

Modulating the magnetosphere of magnetars by internal magneto-elastic oscillations

2014

We couple internal torsional, magneto-elastic oscillations of highly magnetized neutron stars (magnetars) to their magnetospheres. The corresponding axisymmetric perturbations of the external magnetic field configuration evolve as a sequence of linear, force-free equilibria that are completely determined by the background magnetic field configuration and by the perturbations of the magnetic field at the surface. The perturbations are obtained from simulations of magneto-elastic oscillations in the interior of the magnetar. While such oscillations can excite travelling Alfv\'en waves in the exterior of the star only in a very limited region close to the poles, they still modulate the near ma…

PhysicsHigh Energy Astrophysical Phenomena (astro-ph.HE)Astrophysics::High Energy Astrophysical PhenomenaRotational symmetryMagnetosphereFOS: Physical sciencesAstronomy and AstrophysicsMagneto elasticMagnetar01 natural sciencesAsteroseismologyMagnetic fieldNeutron starClassical mechanicsAstrophysics - Solar and Stellar AstrophysicsSpace and Planetary ScienceQuantum electrodynamics0103 physical sciencesMagnetohydrodynamicsAstrophysics - High Energy Astrophysical Phenomena010306 general physics010303 astronomy & astrophysicsSolar and Stellar Astrophysics (astro-ph.SR)
researchProduct

Magneto-elastic torsional oscillations of magnetars

2010

We extend a general-relativistic ideal magneto-hydrodynamical code to include the effects of elasticity. Using this numerical tool we analyse the magneto-elastic oscillations of highly magnetised neutron stars (magnetars). In simulations without magnetic field we are able to recover the purely crustal shear oscillations within an accuracy of about a few per cent. For dipole magnetic fields between 5 x 10^13 and 10^15 G the Alfv\'en oscillations become modified substantially by the presence of the crust. Those quasi-periodic oscillations (QPOs) split into three families: Lower QPOs near the equator, Edge QPOs related to the last open field line and Upper QPOs at larger distance from the equa…

PhysicsHigh Energy Astrophysical Phenomena (astro-ph.HE)HistoryAstrophysics::High Energy Astrophysical PhenomenaEquatorFOS: Physical sciencesMagneto elasticAstrophysicsGeneral Relativity and Quantum Cosmology (gr-qc)MagnetarGeneral Relativity and Quantum CosmologyComputer Science ApplicationsEducationMagnetic fieldNeutron starDipoleAstrophysics - Solar and Stellar AstrophysicsTorsional oscillationsElasticity (economics)Astrophysics - High Energy Astrophysical PhenomenaSolar and Stellar Astrophysics (astro-ph.SR)
researchProduct

Magneto-elastic oscillations and the damping of crustal shear modes in magnetars

2010

In a realistic model of magneto-elastic oscillations in magnetars, we find that crustal shear oscillations, often invoked as an explanation of quasi-periodic oscillations (QPOs) seen after giant flares in soft gamma-ray repeaters (SGRs), are damped by resonant absorption on timescales of at most 0.2s, for a lower limit on the dipole magnetic field strength of 5 10 13 G. At higher magnetic field strengths (typical in magnetars) the damping timescale is even shorter, as anticipated by earlier toy-models. We have investigated a range of equations of state and masses and if magnetars are dominated by a dipole magnetic field, our findings exclude torsional shear oscillations of the crust from ex…

Shear (sheet metal)PhysicsDipoleSpace and Planetary ScienceAstrophysics::High Energy Astrophysical PhenomenaAstronomy and AstrophysicsAstrophysicsResonant absorptionMagneto elasticMagnetohydrodynamicsMagnetarLower limitMagnetic fieldMonthly Notices of the Royal Astronomical Society: Letters
researchProduct