The topology of magnetic reconnection in solar flares

by Des Jardins, Angela Colman.

In order to better understand the location and evolution of magnetic reconnection, which is thought to be the energy release mechanism in solar flares, I combine the analysis of hard X-ray (HXR) sources observed by RHESSI with a three-dimensional, quantitative magnetic charge topology (MCT) model. I first examine the evolution of reconnection by analyzing the relationship between observed HXR footpoint motions and a topological feature called spine lines. With a high degree of confidence, I find that the HXR footpoints sources moved along the spine lines. The standard two dimensional flare model cannot explain this relationship. Therefore, I present a three dimensional model in which the movement of footpoints along spine lines can be understood. To better analyze the location of reconnection, I developed a more detailed method for representing photospheric magnetic fields in the MCT model. This new method can portray internal changes and rotations of photospheric magnetic flux regions, which was not possible with the original method. I then examine the location of reconnection by assuming a relationship between the build-up of energy in stressed coronal magnetic fields and the measurement of the change in separator flux per unit length. I find that the value of this quantity is larger on the separators that connect the HXR footpoint sources than the value on the separators that do not. Therefore, I conclude that we are able to understand the location of HXR sources observed in flares in terms of a physical and mathematical model of the topology of the active region. In summary, based on the success of the MCT model in relating the motion of HXR sources to the evolution of magnetic reconnection on coronal separators, as well as my mathematical and physical model of energy storage at separators, I conclude the MCT model gives useful insight into the relationship between sites of HXR emission and the topology of flare productive active regions. 1