Orateur
Dr
Beresnyak Andrey
(Ruhr University Bochum)
Description
We overview recent progress on small-scale dynamo and apply
the results to the the problem of nonlinear shock acceleration in which
particle mean free paths in front of the shock are greatly reduced
due to magnetic fields in the shock precursor which are generated
through small-scale dynamo in the density gradient's-induced
turbulence. Previous DSA models considered magnetic fields amplified through
cosmic ray streaming instabilities either by way of individual particles
scattering in the magnetic fields, or by macroscopic electric currents
associated with large-scale cosmic ray streaming. The small-scale
dynamo mechanism provides fast growth and is very generic. For
supernovae shocks this mechanism is estimated to generate upstream
magnetic fields that are sufficient for accelerating cosmic rays up
to around 10^16 eV.
