Pulsating solar radio emission

Abstract

A status report of current research on pulsating radio emission is given, based on working group discussions at the CESRA 2004 workshop. Quasi-periodic pulsations have been observed at all wavelength ranges of the radio band. Usually, they are associated with flare events; however since the late 90s, pulsations of the slowly-varying component of the Sun's radio emission have also been observed. Radio pulsations show a large variety in their periods, bandwidths, amplitudes, temporal and spatial signatures. Most of them have been attributed to MHD oscillations in coronal loops, while alternative interpretations consider intrinsic oscillations of a nonlinear regime of kinetic plasma instabilities or modulation of the electron acceleration. Combined radio spectroscopic observations with radio imaging and X-ray/EUV data have revived interest in the subject. We summarize recent progress in using radio pulsations as a powerful tool for coronal plasma and magnetic field diagnostics. Also the latest developments on the study of the physical processes leading to radio emission modulation are summarized. © 2007 Springer.