DETECTION OF MICROWAVE EMISSION FROM CORONAL X-RAY JETS

We present evidence of the detection of microwave emission at 17 GHz i n association with coronal X-ray jets. We present two typical cases-on e on the disk (1995 March 31) and the other at the limb (1992 August 2 5). For the disk event we see 17 GHz emission from the upper part of t he jet base (active region loop or loops), but no emission from the co llimated X-ray jet itself, implying that it must be optically thin at 17 GHz. For the limb event, we see the base of the jet as well as the bottom part of the jet itself, implying that the optical depth is high er at the bottom part (obviously because of higher electron density) t han at the top. We believe that the 17 GHz emission is thermal, becaus e it is gradual and unpolarized, and that the heating process that giv es rise to the jet X-ray plasma also results in the 17 GHz emission. T he calculated 17 GHz flux densities seem to agree with the observed va lues within a factor of 2. We consider this disagreement to be quite r easonable in view of the various uncertainties involved in computing t he emission in both radio and X-rays.