STIX electron flux maps allow the quantitative determination of the number of accelerated electrons in solar flares

This talk shows that imaging-spectroscopy analyses from data recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) on-board Solar Orbiter allow to disentangle the two factors that determine the observed hard X-ray spectrum of a solar flare, i.e., the density of the accelerated electrons and the ambient target density. More specifically, we show, for the first time in a quantitative way, that in the case of some peculiar events characterized by a significant coronal emission, the number of non-thermal electrons accelerated by the flare is relatively small and that a high rate of such electrons is stopped before they can reach the chromosphere