From kink instability to magnetic reconnection to oscillations in solar flares

Abstract

We show how some different fundamental plasma processes - the ideal kink instability, magnetic reconnection and magnetohydrodynamic oscillations - can be causally linked. This is shown through reviewing a series of models of energy release in twisted magnetic flux ropes in the solar corona, representing confined solar flares. 3D magnetohydrodynamic simulations demonstrate that fragmented current sheets develop during the nonlinear phase of the ideal kink instability, leading to multiple magnetic reconnections and the release of stored magnetic energy. By coupling these simulations with a test particle code, we can predict the development of populations of non-thermal electrons and ions, as observed in solar flares, and produce synthetic observables for comparison with observations. We also show that magnetic oscillations arise in the reconnecting loop, although there is no oscillatory external driver, and these lead to pulsations in the microwave emission similar to observed flare quasi-periodic pulsations. Oscillations and propagating waves also arise from reconnection when two twisted flux ropes merge, which is modelled utilising 2D magnetohydrodynamic simulations.