Relative timing of electron acceleration and injection at solar flares: A case study

Abstract

Multiple-wavelength observations of a C-class solar flare and in situ measurements of high-energy electrons at 1 AU are combined for a detailed analysis of the relative timing of solar electromagnetic emission and high-energy electron injection. The primary energy release for the C8.0 flare on 2002 June 02 (10:05–10:30 UT) is studied using hard X-ray data of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The propagation of disturbances through the solar corona and interplanetary space is investigated by means of dynamic radio spectra obtained by ground-based observatories (Ondřejov, Czech Republic, and Potsdam, Germany). The time sequence of these indirect manifestations of highly energetic electrons is correlated with the extrapolated injection time obtained by a transit time analysis from Sun to Earth using the enhancement in the 27–182 keV electron intensity observed at the Wind spacecraft. This back-mapping of high-energy electrons shows that the particles are injected roughly 18 min after the first hard X-ray maximum. Almost at the same time there are observations of metric type II and IV radio bursts indicating the presence of a coronal shock wave and a moving plasmoid whose kinematics are analysed by means of dynamic radio spectra and radio images from the Nançay Radioheliograph (France). Implications for possible acceleration and injection scenarios are discussed.