Physics @ Berkeley
Events in Physics
Title: 290B Space Physics Seminar    (Seminar)
Start Date: 02/13/2006
Time: 1:45 pm
Location: 508-30 Evans
Speaker: Nicole Vilmer
Affiliation: Observatoire de Paris
Contact Person: Sam Lam   (510) 642-7297

Multi-wavelength Observations of Energetic Electrons and Ions Accelerated in
Solar Flares




Observatoire de Paris



Explosive phenomena of magnetic energy conversion in the solar corona lead to the production of energetic particles at all energies. These energetic particles play a major role in the active Sun since they contain a large amount of the energy released during flares. The most quantitative diagnostics of energetic particles interacting at the Sun are given by X-ray and g-ray observations such as the ones obtained with the RHESSI mission. Complementary observations of the Hard X-ray producing electrons are provided by the radio emissions produced in the whole frequency range from 100 GHz to a few MHz.  While radio observations from submm to cm wavelengths provide complementary quantitative diagnostics on the spectra and number of energetic electrons together with some indication on the magnetic field and density in the emitting sites, plasma radiation in the decimetric/metric domains gives information on the  supra-thermal electrons present in the low and middle corona in connection with flares.

In this talk, I shall present some results obtained recently from multi-wavelength observations of several flares observed in the HXR domain by RHESSI and at radio wavelengths by the Nançay Radioheliograph and radiometers in Bern. I shall report in particular on observations of broad-band modulations observed in HXR and radio in late phase of flares in possible connection with CME’s and also discuss the relationship between HXR and radio emitting electrons. I shall also present the results of a simulation of electron and ion acceleration in solar flares based on cellular automata models for energy release and on acceleration by direct electric fields in current sheets. The predictions of  HXR and gamma-ray emissions will be compared to the observed of the emissions.