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An Observed Correlation between the Flux Densities of Extended Hard X-ray and Microwave Solar Bursts

Published online by Cambridge University Press:  25 April 2016

R. T. Stewart  and
G. J. Nelson
R. T. Stewart
Affiliation:
Division of Radiophysici, CSIRO, Sydney
G. J. Nelson
Affiliation:
Division of Radiophysici, CSIRO, Sydney
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Extract

Crannell et al. (1978) have reported an observed correlation between the time profiles and flux densities of impulsive hard X-ray and microwave solar bursts. We report here on a significant correlation between the flux density of extended bursts of hard X-rays and micowaves. These extended events follow after impulsive bursts and last much longer (see e.g. Fig. 1, Frost and Dennis 1971). However, as extended bursts only occur during very large flares the number of cases available for study is small. The significance of our observations follows from the suggestion of Wild et al. (1963) that the extended bursts are evidence for a second-phase acceleration process in the corona. We show that the observed characteristics of these extended microwave bursts (viz. a rather flat spectrum below a turnover frequency which is independent of intensity) can be explained by gyro-synchrotron radiation from the same population of energetic (E ≈ 100 keV) electrons as those emitting (thin-target) X-ray bremsstrahlung. A detailed source model is discussed in a companion paper (Nelson and Stewart 1979 — Paper B).

Type
Contributions
Information
Publications of the Astronomical Society of Australia , Volume 3 , Issue 6 , 1979 , pp. 390 - 392
Copyright
Copyright © Astronomical Society of Australia 1979

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