Signatures of Magnetic Stress Prior to Three Solar Flares Observed by RHESSI

Abstract

We examine the hard X-ray (HXR) footpoint sources of three flares, as observed by RHESSI, in combination with the topology given by the extrapolation of line-of-sight magnetograms into the corona. Assuming the HXR footpoint sources are chromospheric consequences of magnetic reconnection that takes place on separators, we further assume a relationship between the buildup of energy in stressed coronal magnetic fields and the measurement of the change in separator flux per unit length. We find that the value of this quantity is larger for the separators that connect the HXR footpoint sources than the quantity for the separators that do not. Therefore, we 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.