AlfvÌ©n QPOs in Magnetars in the anelastic approximation
December 16, 2009
Abstract: AlfvÌ©n 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.