Zeeman splitting of torsional oscillation frequencies of magnetars
arXiv:2312.10022 · doi:10.3390/universe9120504
Abstract
Magnetars form a special class of neutron stars possessing superstrong magnetic fields and demonstrating power flares triggered likely by these fields. Observations of such flares reveal the presence of quasi-periodic oscillations (QPOs) at certain frequencies; they are thought to be excited in the flares. QPOs carry potentially important information on magnetar structure, magnetic field, and mechanisms of magnetar activity. We calculate frequencies of torsional (magneto-elastic) oscillations of the magnetar crust treating the magnetic field effects in the first order of perturbation theory. The theory predicts splitting of non-magnetic oscillation frequencies into Zeeman components. Zeeman splitting of torsional oscillation spectrum of magnetars was suggested, clearly described and estimated by Shaisultanov and Eichler (2009) but their work has not been given considerable attention. To extend it we suggest the technique of calculating oscillation frequencies including Zeeman splitting at not too strong magnetic fields for arbitrary magnetic field configuration. Zeeman splitting enriches the oscillation spectrum and simplifies theoretical interpretation of observations. We calculate several low-frequency oscillations of magnetars with pure dipole magnetic field in the crust. The results qualitatively agree with low-frequency QPOs detected in the hyperflare of SGR 1806--20, and in the giant flare of SGR 1900+14.
arXiv comment15 pages, 3 figures, typos in eqs. (26) and (27) corrected
References in corpus (46)
- Magnetars
- The McGill Magnetar Catalog
- Discovery of Rapid X-ray Oscillations in the Tail of the SGR 1806-20 Hyperflare
- Analytical representations of unified equations of state for neutron-star matter
- Magnetars: Properties, Origin and Evolution
- Global Seismic Oscillations in Soft Gamma Repeaters
- Neutron Star Asteroseismology. Axial Crust Oscillations in the Cowling Approximation
- Detection with RHESSI of high frequency X-ray oscillations in the tail of the 2004 hyperflare from SGR 1806-20
- Analytical representations of unified equations of state of neutron-star matter
- 2D Cooling of Magnetized Neutron Stars
- 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
- Probing the Equation of State of Nuclear Matter via Neutron Star Asteroseismology
- On the theory of magnetar QPOs
- Elastic or magnetic? A toy model for global magnetar oscillations with implications for QPOs during flares
- Magnetars oscillations in the presence of a crust
- Effect of superfluidity on neutron star crustal oscillations
- 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
- Possible Constraints on the Density Dependence of the Nuclear Symmetry Energy from Quasiperiodic Oscillations in Soft Gamma Repeaters
- Magnetar Oscillations I: strongly coupled dynamics of the crust and the core
- On the Quasi-Periodic Oscillations of Magnetars
- Quasi-Periodic Oscillations in Short Recurring Bursts of the Soft-Gamma Repeater J1550-5418
- Superfluid signatures in magnetar seismology
- Magneto-elastic oscillations of neutron stars: exploring different magnetic field configurations
- Quasi-periodic oscillations in superfluid magnetars
- 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
- Constraints on the nuclear equation of state and the neutron star structure from crustal torsional oscillations
- Magnetar Oscillations II: spectral method
- Probing nuclear bubble structure via neutron star asteroseismology
- Axisymmetric toroidal modes of magnetized neutron stars
- Astrophysical implications of double-layer torsional oscillations in a neutron star crust as a lasagna sandwich
- Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations
- Bayesian timing analysis of giant flare of SGR 1806-20 by RXTE PCA
- Coherent magneto-elastic oscillations in superfluid magnetars
- Probing crustal structures from neutron star compactness
- Torsional Oscillations of a Magnetar with a Tangled Magnetic Field
- Neutron star mass-radius constraints using the high-frequency QPOs of GRB 200415A
- Deformed crystals and torsional oscillations of neutron star crust
- Search for quasi-periodic signals in magnetar giant flares
- Empirical formula of crustal torsional oscillations
- What Magnetar Seismology can Teach us about the Magnetic Fields
- Selfsimilarity relations for torsional oscillations of neutron stars