Magnetic Torsional Oscillations in Magnetars

Journal Article · Fri May 01 04:00:00 EDT 2009 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3141338· OSTI ID:21304822

Sotani, Hajime ^[1]; Kokkotas, Kostas D ^[1]; Stergioulas, Nikolaos ^[2]

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1. Theoretical Astrophysics, University of Tuebingen, 72076, Tuebingen (Germany)
2. Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)

We investigate torsional Alfven oscillations of relativistic stars with a global dipole magnetic field, via 2D numerical simulations. We find that a) there exist two families of quasi-periodic oscillations (QPOs) with harmonics at integer multiples of the fundamental frequency, b) the QPOs are long-lived, c) for the chosen form of dipolar magnetic field, the frequency ratio of the lower to upper fundamental QPOs is about 0.6, independent of the equilibrium model or of the strength of the magnetic field, and d) within a representative sample of EOS and of various magnetar masses, the Alfven QPO frequencies are given by accurate empirical relations that depend only on the compactness of the star and on the magnetic field strength. Compared to the observational frequencies, we also obtain an upper limit on the strength of magnetic field of SGR 1806-20 (if is dominated by a dipolar component) between {approx}3 and 7x10{sup 15} Gauss.

• OSTI ID: 21304822
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1122; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ALFVEN WAVES
COMPUTERIZED SIMULATION
COSMOLOGICAL MODELS
COSMOLOGY
DIPOLES
HARMONICS
HYDROMAGNETIC WAVES
INTERSTELLAR MAGNETIC FIELDS
LUMINESCENCE
PERIODICITY
RELATIVISTIC RANGE
STARS