Coherent magneto-elastic oscillations in superfluid magnetars
arXiv:1605.07638 · doi:10.1093/mnras/stw1272
Abstract
We study the effect of superfluidity on torsional oscillations of highly magnetised neutron stars (magnetars) with a microphysical equation of state by means of two-dimensional, magnetohydrodynamical- elastic simulations. The superfluid properties of the neutrons in the neutron star core are treated in a parametric way in which we effectively decouple part of the core matter from the oscillations. Our simulations confirm the existence of two groups of oscillations, namely continuum oscillations that are confined to the neutron star core and are of Alfvénic character, and global oscillations with constant phase and that are of mixed magneto-elastic type. The latter might explain the quasi-periodic oscillations observed in magnetar giant flares, since they do not suffer from the additional damping mechanism due to phase mixing, contrary to what happens for continuum oscillations. However, we cannot prove rigorously that the coherent oscillations with constant phase are normal modes. Moreover, we find no crustal shear modes for the magnetic field strengths typical for magnetars.We provide fits to our numerical simulations that give the oscillation frequencies as functions of magnetic field strength and proton fraction in the core.
arXiv comment16 pages, 12 figures, accepted by MNRAS
References in corpus (65)
- The equation of state for nucleon matter and neutron star structure
- A unified equation of state of dense matter and neutron star structure
- Isospin Asymmetry in Nuclei and Neutron Stars
- The McGill Magnetar Catalog
- Physics of Neutron Star Crusts
- Electrodynamics of Magnetars: Implications for the Persistent X-ray Emission and Spindown of the Soft Gamma Repeaters and Anomalous X-ray Pulsars
- Comparing Models of Rapidly Rotating Relativistic Stars Constructed by Two Numerical Methods
- Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter
- Cooling neutron star in the Cassiopeia~A supernova remnant: Evidence for superfluidity in the core
- Discovery of Rapid X-ray Oscillations in the Tail of the SGR 1806-20 Hyperflare
- Hyperon stars in the Brueckner-Bethe-Goldstone theory
- Discovery of Fast X-ray Oscillations During the 1998 Giant Flare from SGR 1900+14
- Global Seismic Oscillations in Soft Gamma Repeaters
- Neutron conduction in the inner crust of a neutron star in the framework of the band theory of solids
- Neutron Star Asteroseismology. Axial Crust Oscillations in the Cowling Approximation
- The 2004 Hyperflare from SGR 1806-20: Further Evidence for Global Torsional Vibrations
- Detection with RHESSI of high frequency X-ray oscillations in the tail of the 2004 hyperflare from SGR 1806-20
- Magnetohydrodynamics of superfluid and superconducting neutron star cores
- Torsional Oscillations of Relativistic Stars with Dipole Magnetic Fields
- QPOs during magnetar flares are not driven by mechanical normal modes of the crust
- Magneto-elastic oscillations of neutron stars with dipolar magnetic fields
- On the theory of magnetar QPOs
- Constraints on Neutron Star Crusts From Oscillations in Giant Flares
- Shear Waves and Giant Flare Oscillations from Soft Gamma-Ray Repeaters
- Upper limits on the observational effects of nuclear pasta in neutron stars
- Elastic or magnetic? A toy model for global magnetar oscillations with implications for QPOs during flares
- Alfvén QPOs in Magnetars
- Magnetars oscillations in the presence of a crust
- Effect of superfluidity on neutron star crustal oscillations
- Oscillations of General Relativistic Superfluid Neutron Stars
- A new general relativistic magnetohydrodynamics code for dynamical spacetimes
- Magneto-elastic oscillations and the damping of crustal shear modes in magnetars
- Coupled polar-axial magnetar oscillations
- Alfven QPOs in magnetars in the anelastic approximation
- On the Quasi-Periodic Oscillations of Magnetars
- Magnetar Oscillations I: strongly coupled dynamics of the crust and the core
- Superfluid signatures in magnetar seismology
- Quasi-Periodic Oscillations in Short Recurring Bursts of the Soft-Gamma Repeater J1550-5418
- Magneto-elastic oscillations of neutron stars: exploring different magnetic field configurations
- Two-fluid models of superfluid neutron star cores
- The entrainment matrix of a superfluid neutron-proton mixture at a finite temperature
- Magnetic Field Evolution in Superconducting Neutron Stars
- Magnetohydrodynamics in Superconducting-Superfluid Neutron Stars
- Quasi-periodic oscillations in superfluid magnetars
- Adiabatic oscillations of non-rotating superfluid neutron stars
- Quasi-Periodic Oscillations in Short Recurring Bursts of the magnetars SGR 1806-20 and SGR 1900+14 Observed With RXTE
- Imprints of superfluidity on magneto-elastic QPOs of SGRs
- Magnetar superconductivity versus magnetism: neutrino cooling processes
- Torsional Oscillations of Magnetized Relativistic Stars
- Stratification, superfluidity and magnetar QPOs
- Possible identifications of newly observed magnetar quasi-periodic oscillations as crustal shear modes
- Magnetar Oscillations II: spectral method
- Hydromagnetic waves in a superfluid neutron star with strong vortex pinning
- Axial quasi-normal modes of neutron stars: Accounting for the superfluid in the crust
- Constraining the Origin of Magnetar Flares
- Lagrangian perturbation theory of nonrelativistic rotating superfluid stars
- Bayesian timing analysis of giant flare of SGR 1806-20 by RXTE PCA
- Modulating the magnetosphere of magnetars by internal magneto-elastic oscillations
- Intermittency and Lifetime of the 625 Hz QPO in the 2004 Hyperflare from the Magnetar SGR 1806-20 as evidence for magnetic coupling between the crust and the core
- Magnetar giant flare oscillations and the nuclear symmetry energy
- Torsional Oscillations of a Magnetar with a Tangled Magnetic Field
- Three evolutionary paths for magnetar oscillations
- Numerical viscosity in hydrodynamics simulations in general relativity
- Torsional oscillations of neutron stars with highly tangled magnetic fields
- Magnetized neutron stars with superconducting cores: Effect of entrainment
Cited by in corpus (21)
- Spectrum of shear modes in the neutron-star crust: Estimating the nuclear-physics uncertainties
- Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations
- A superfluid perspective on neutron star dynamics
- On the Persistence of QPOs During the SGR 1806-20 Giant Flare
- Quasi-periodic oscillations in precursor flares via seismic aftershocks from resonant shattering
- Deformed crystals and torsional oscillations of neutron star crust
- Neutron star mass-radius constraints using the high-frequency QPOs of GRB 200415A
- Quasi-periodic oscillations in superfluid, relativistic magnetars with nuclear pasta phases
- Search for quasi-periodic signals in magnetar giant flares
- Hydrodynamical instabilities in superfluid neutron stars with background flows between the components
- Premerger phenomena in neutron-star binary coalescences
- An Intermediate-field Fast Radio Burst Model and the Quasi-periodic Oscillation
- Quasi-periodic oscillations during magnetar giant flares in the strangeon star model
- A revised formalism for slowly-rotating superfluid neutron stars in general relativity
- Powerful flares and magneto-elastic oscillations of magnetars
- Zeeman splitting of torsional oscillation frequencies of magnetars
- Selfsimilarity relations for torsional oscillations of neutron stars
- Axisymmetric magnetic modes of neutron stars having mixed poloidal and toroidal magnetic fields
- Magneto-elastic oscillations modulating the emission of magnetars
- Nonlinear coupling between magnetar QPOs
- Zeeman effect in oscillations of magnetars with toroidal magnetic fields