I was asked to give a broad-minded review of magnetar QPO theory.
Here are the issues I plan to discuss:
1. Are we sure that magnetar QPOs are due to oscillations of neutron star?
My viewpoint: not completely, but so far no plausible alternative exists.
2. What triggers SGR flare and how is it coupled to excitation of oscillations?
My viewpoint: magnetosphere rather than crust
3. Do we understand how NS motion is coupled to x-ray flux modulation?
My viewpoint: no
4. What do and don't we understand about the dynamics of NS oscillations?
My viewpoint: do - General Relativity
don't (to various degrees) - crust shear modulus, superfluidity, MHD
The talk is meant to complement those of Watts and van Hoven.