Speaker
Urs Ganse
(University of Helsinki)
Description
Heliospheric shocks are well-known accelerators of particles, responsible for
the creation of gradual solar energetic particle events. While the fact that
particle beams are formed in shock interactions is firmly established, many
open questions remain in regard to the microphysics of the acceleration process
and the shape of the resulting beam distribution.
The standard analytic assumption for the distribution functions of
shock-accelerated particle beams is that of a gyrotropic loss-cone
distribution. However, using two independent simulation methods (test-particle
simulations and hybrid-Vlasov simulations) we have identified situations in
which the presence of foreshock waves leads to the formation of beams with
distribution functions departing significantly from this prediction.
In particular, helical, highly non-gyrotropic beam structures in velocity space
appear upstream of fluctuating shock structures.
We identify the origins of these helix structures at the shock, analyze the
instability behaviour of these beams and discuss observational signatures from
synthetic observations.
| Registration number following "ICRC2015-I/" | 792 |
|---|---|
| Collaboration | -- not specified -- |
Primary author
Urs Ganse
(University of Helsinki)
Co-authors
Alex Ivascenko
(North-West University)
Felix Spanier
(North-West University)
Minna Palmroth
(Finnish Meteorological Institute)
Rami Vainio
(University of Turku)
Sebastian van Alfthan
(Finnish Meteorological Institute)
Yann Pfau-Kempf
(Finnish Meteorological Institute)
