Cosmic ray acceleration in young supernova remnants
  We investigate the appearance of magnetic field amplification resulting from
a cosmic ray escape current in the context of supernova remnant shock waves.
The current is inversely proportional to the maximum energy of cosmic rays, and
is a strong function of the shock velocity. Depending on the evolution of the
shock wave, which is drastically different for different circumstellar
environments, the maximum energy of cosmic rays as required to generate enough
current to trigger the non-resonant hybrid instability that confines the cosmic
rays follows a different evolution and reaches different values. We find that
the best candidates to accelerate cosmic rays to ~few PeV energies are young
remnants in a dense environment, such as a red supergiant wind, as may be
applicable to Cassiopeia A. We also find that for a typical background magnetic
field strength of 5 microG the instability is quenched in about 1000 years,
making SN1006 just at the border of candidates for cosmic ray acceleration to
high energies.
