Solar Magnetic Reconnection at Low Altitudes and Associated Type III Solar Radio Bursts and X-Ray Emission

Abstract:

Magnetic reconnection events are identified definitively in Solar Dynamics Observatory (SDO) data on 25 September 2011, with double-sided jets, current sheets and cusp-like geometries on top of loops, and strong outflows at 200 km/s along pairs of open magnetic field lines. Strong type III bursts observed by the Learmonth radio spectrograph and imaged by the MurchisonWidefield Array (MWA) are demonstrated to be in very good temporal and spatial coincidence with specic SDO magnetic reconnection events and with bursts of nonthermal 3-35 keV X-rays observed by the RHESSI spacecraft. The reconnection sites are low, near heights of 5-10 Mm or 0.01 solar radii, alleviating the number problem for producing the energetic electrons and X-rays. These data, especially the images and event timings, provide direct evidence for the long-unproven but standard model for type III bursts: semi-relativistic electrons energized in magnetic reconnection regions produce radio emission as they move away from the Sun and X-rays as they move into the chromosphere. Since not all SDO events produce X-ray or type III events, different special conditions must exist for the production of strong radio, X-ray, or UV bursts by reconnection events. These conditions are both on the production of suitable energetic electrons and on the production of observable radio, X-ray, and UV emissions from these electrons.