EVIDENCE FOR ENHANCED MHD TURBULENCE OUTSIDE SHARP-RIMMED SUPERNOVA-REMNANTS

We consider the propagation of synchrotron-emitting electrons near the shocks of supernova remnants. Using high-resolution radio observation s of four Galactic supernova remnants, we set upper limits on the scat tering mean free paths of these electrons in front of the supernova sh ock fronts. It is shown that for the sharpest rims, this mean free pat h is typically less than one percent of that derived for cosmic rays o f similar rigidity in the interstellar medium. This result is interpre ted in terms of an enhanced hydromagnetic wave intensity generated by diffusive shock acceleration. The dimensionless intensities of the sca ttering waves near supernova remnants are shown to be J(SNR)(5 GV/c) g reater-than-or-equal-to 6 x 10(-4), in contrast to typical interstella r values J(ISM)(5 GV/c) less-than-or-equal-to 10(-5). where the intens ity J = (deltaB/B)2, where deltaB is the amplitude of the waves with w avelengths resonant with particles of the specified rigidities. For SN R parameters, these wavelengths are of order 10(12) - 10(13) cm. Highe r resolution radio and X-ray observations should provide useful diagno stics of the details of particle acceleration in these environments.