Study of combined soft and hard X-ray images of solar flares

We have studied soft and hard X-ray images of 13 solar flares from six active regions observed by the Hard X-ray Imaging Spectrometer (HXIS). Our results indicate the presence of pre-hard X-ray burst excesses in the 11.5–30.0 keV range, indicating a slow buildup of the acceleration process or a strong preheating. During the impulsive phase, all of the events show the simultaneous energization of neighboring field structures, which, in the case we show in some detail, share about equal amounts of the released energy. This association seems to be indicative of strong acceleration and energy release triggered by the interaction between magnetic loops.