Alfv̩n QPOs in Magnetars in the anelastic approximation

Pablo CerdÌÁ-DurÌÁn

December 16, 2009

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Abstract: Alfv̩n oscillations of magnetars coupled to shear modes in the crust could possibly explain the quasi-periodic oscillations (QPOs) observed in the giant flares of soft gamma repeaters. I present results of two-dimensional simulations of Alfven torsional oscillations in magnetars, modeled as relativistic stars with a dipolar magnetic field. We use a general relativistic magnetohydrodynamics code in the anelastic approximation, which allows for an effective suppression of fluid modes and an accurate description of the Alfven waves. We present also a new method to compute the QPOs frequencies and compare it to the numerical results.