Microwave, hard x-ray bursts and gamma ray emission bursts from solar flares

A study has been carried out on the time delay between microwave (MW) emissions at 35 GHz, hard X-ray (HXR) emissions (> 25 keV) and gamma ray (GR) emissions (> 300 keV) observed during solar flares. The GR emissions are found to start about 1 min after the onset of HXR emissions during impulsive flares and 4 min after the onset of HXR emissions during extended solar flares, indicating that impulsive and extended solar flares are two different types of flares and may have different mechanisms of origin. The onset time delays in GR and HXR emissions are due to the differences in kinetic energy of electrons to produce GR and HXR photons. The investigation regarding onset time delays between GR and MW emissions has also been carried out. The GR emissions are found to start 1 min after the onset of MW emissions during impulsive flares. The MW and GR emissions originate from different mechanisms operating at different heights and are produced by electrons with differing energies, thus producing time delays. Further, it is observed that MW emissions may not be produced by relativistic electrons as suggested by some investigators. (author). 5 figs., 22 refs