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| Paper: |
Relativistic MHD Simulations of Alfvén QPOs in Magnetars |
| Volume: |
429, Numerical Modeling of Space Plasma Flows, Astronum-2009 |
| Page: |
72 |
| Authors: |
Font, J. A.; Cerdá -Durán, P.; Stegioulas, N. |
| Abstract: |
Results from two-dimensional simulations of Alfvén oscillations in magnetars are presented, modeled as relativistic stars with a dipolar magnetic field. We use the anelastic approximation to general relativistic magnetohydrodynamics, which allows for an effective suppression of fluid modes and an accurate description of Alfvén waves. In addition, we compute Alfvén oscillation frequencies along individual magnetic field lines with a semi-analytic approach. Our work confirms previous results based on perturbative approaches regarding the existence of two families of quasi-periodic oscillations (QPOs), with harmonics at integer multiples of the fundamental frequency. Empirical relations for the QPO frequencies are constructed and compared to observations of known Soft Gamma Repeaters. Under the assumptions of our model our results place an upper limit to the mean surface strength of the magnetic field of about 3–8×1015G. |
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