Le séminaire a lieu le vendredi
10 octobre 2003 de 14h30 à 15h30
dans la salle de réunion
du PHC (Observatoire de Nice).
Electron pre-acceleration at supernova remnant shocks
Synchrotron radiation from the shock region of supernova
remnants provides
evidence for extremely energetic electrons. Fermi acceleration
can partly
explain these fast electrons. However the particles have
to possess a minimum
energy for Fermi acceleration to set in. This calls for
a preacceleration
mechanism, the nature of which in not known. Simple shock
drift acceleration
cannot supply the necessary energies.
Particle in cell simulations of perpendicular shocks have
been carried out and
show that electrons can be accelerated in the shock foot
region where the
inflowing ions and reflected ions form instabilities
with the electron
population.