##
Evidence for enhanced MHD turbulence outside sharp-rimmed
supernova
remnants

Achterberg, A.; Blandford, R. D.; Reynolds, S. P.
*Published in:*
A&A, 281, 220

### Abstract

We consider the propagation of synchrotron-emitting electrons near the shocks
of supernova remnants
(SNRs). Using high-resolution radio observations of four Galactic supernova
remnants, we set upper limits
on the scattering mean free paths of these electrons in front of the supernova
shock fronts. It is shown that
for the sharpest rims, this mean free path is typically less than one percent
of that derived for cosmic rays
of similar rigidity in the interstellar medium. This result is interpreted in
terms of an enhanced
hydromagnetic wave intensity generated by diffusive shock acceleration. The
dimensionless intensities of
the scattering waves near supernova remnants are shown to be Tau(sub SNR)(5
GV/c) greater than or equal
to 6 x 10(exp -4), in contrast to typical interstellar values Tau(sub ISM)(5
GV/c) less than or equal to
10(exp -5), where the intensity Tau = (delta B/B)(exp 2), where delta B is the
amplitude of the waves with
wavelengths resonant with particles of the specified rigidities. For SNR
parameters, these wavelengths are
of order 10(exp 12) - 10(exp 13) cm. Higher resolution radio and X-ray
observations should provide useful
diagnostics of the details of particle acceleration in these environments.