Radio and Hard X–ray Images of High–Energy Electrons in a Compact X-class Solar Flare

We present the first comparison between radio images of high–energy electrons accelerated by a solar flare and images of hard X–rays produced by the same electrons at photon energies above 100 keV. The radio and hard X–ray light curves match each other well and both light curves and spectra are quantitatively consistent with an origin in a single population of nonthermal electrons with a power law index of around 4.5– 5. The images indicate that the radio emission comes from an arcade of loops, with hard X–rays from their footpoints. Radio brightness temperatures exceed 109 K and the peak in the radio spectrum is as high as 30 GHz: both these features point to very high densities of nonthermal electrons, possibly as high as 1011 cm−3 above 10 keV at the peak of the flare. Subject headings: Sun: flares – Sun: corona – Sun: radio radiation