Abstract

Interaction between two loops, one of which is a small, newly emerging loop, and another one of which is a large overlying loop, is a typical cause of solar flares and related active phenomena. We revealed the configuration of an emerging loop and an overlying loop using microwave and soft X-ray observations of the flares, along with their magnetograms. Two of the footpoints of the loops, one from the emerging loop and the other from the overlying loop, are included in a single magnetic polarity patch. The two loops form a `three-legged' structure, and the magnetic field has a `bipolar + remote unipolar' structure. Relative timing analysis of the brightness of the microwave and hard X-ray sources based on the high-temporal resolution data shows that the brightness fluctuation of the remote source is delayed by 400--600 ms to that of the main source, which is located at the interacting region of the two loops. This is the evidence that the electron acceleration site is located at the interaction region of the two loops.