Rayleigh-Taylor Type Instabilities in the Reconnection Exhaust Jet as a Mechanism for Supra-arcade Downflows
Lijia Guo (Max Planck Institute for Solar System Research)
Abstract. Supra-arcade downflows (hereafter referred to as SADs) are low-emission, elongated, finger-like features observed in active-region coronae above post-eruption flare arcades. Observations exhibit downward moving SADs intertwined with bright upward growing spikes. Although SADs have been observed for more than a decade, the mechanism of formation of SADs remains an open issue. Using 3D resistive MHD simulations, we demonstrate that Rayleigh-Taylor type instabilities develop in the downstream region of a reconnecting current sheet. The instabilities result in the formation of low-density coherent structures that resemble SADs, and high-density structures that appear to be spike-like. Comparison between the simulation results and observations suggests that Rayleigh-Taylor type instabilities in the exhaust of reconnecting current sheets provide a plausible mechanism for observed SADs.
Contributed Talk
