Alfvén QPOs in Magnetars in the anelastic approximation

Pablo Cerdá-Durán (MPA)

Alfvén 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.