Evidence for a common origin of the electrons responsible for the impulsive X-ray and type III radio bursts.

Observations of impulsive solar flare X-rays greater than or about equal to 10 keV made with the OGO-5 satellite are compared with ground-based measurements of type III solar radio bursts in 10- to 580-MHz range. It is shown that the times of maxima of these two emissions, when detectable, agree within about 18 sec. This maximum time difference is comparable to that between the maxima of the impulsive X-ray and impulsive microwave bursts. In view of the various observational uncertainties, it is argued that the observations are consistent with the impulsive X-ray, impulsive microwave, and type III radio bursts being essentially simultaneous. The observations are also consistent with 10- to 100-keV electron streams being reponsible for the type III emission. The observations indicate that the non-thermal electron groups responsible for the impulsive X-ray, impulsive microwave, and type III radio bursts are accelerated simultaneously in essentially the same region of the solar atmosphere.