Ripples in a Stormy Sea: Variability and Quasi-Periodic Oscillations in Magnetar Bursts

Periodic and quasi-periodic oscillations constitute some of the most interesting and constraining signals in astronomical light curves. They imply that the process that caused the signal varies on a regular time scale, and are thus often very informative for constraining the physics of the system. In magnetars, the detection of quasi-periodic oscillations in the tails of Giant Flares and magnetar short bursts has opened up the exciting prospect of neutron star seismology, where they can be used as powerful probes of the neutron star crust and interior. Detecting these signals is challenging, however, because magnetar bursts and flares show an extremely rich phenomenology in their variability. While this variability confounds our periodicity detection algorithms, it also presents exciting new avenues to study magnetar physics. In this talk, I will give an overview of the variability properties of magnetar bursts and flares, including both quasi-periodic and non-periodic variability. I will lay out how we can use the variability to constrain magnetar physics, highlight recent observational discoveries and share future challenges to be addressed.