Detection of Microwave Emission from Coronal X-Ray Jets

Abstract

We present evidence of the detection of microwave emission at 17 GHz in association with coronal X-ray jets. We present two typical cases—one on the disk (1995 March 31) and the other at the limb (1992 August 25). For the disk event we see 17 GHz emission from the upper part of the jet base (active region loop or loops), but no emission from the collimated 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 higher at the bottom part (obviously because of higher electron density) than at the top. We believe that the 17 GHz emission is thermal, because it is gradual and unpolarized, and that the heating process that gives rise to the jet X-ray plasma also results in the 17 GHz emission. The calculated 17 GHz flux densities seem to agree with the observed values within a factor of 2. We consider this disagreement to be quite reasonable in view of the various uncertainties involved in computing the emission in both radio and X-rays.