The numbers of fast electrons in solar flares as deduced from hard X-ray and microwave spectral data

Abstract

The previously reported discrepancy between the number of fast solar flare electrons deduced from hard X-ray burst observations and microwave observations of the same events is reexamined. The thin and thick-target models for hard X-ray production and their consequences for gyrosynchrotron emission of microwaves are discussed. Previous work that led to the perceived discrepancy is reviewed, and it is suggested that the discrepancy can be reduced when thick-target hard X-ray emission is assumed. The number of electrons in microwaves and hard X-rays are calculated assuming a homogeneous source for a sample of flares given by Wiehl et al. (1983). The numbers are given separately under the two assumptions of thin and thick-target hard X-ray emission. It is found that when the latter emission is assumed, the number of electrons deduced from the microwaves is very similar to the number deduced from the hard X-rays. 36 references.