##
Model images of radio halos around supernova
remnants

Reynolds, Stephen P.
*Published in:*
ApJ, 90, 845

### Abstract

I present model calculations of profiles and two-dimensional images of the
radio synchrotron emission of
young supernova remnants, concentrating on observable effects of relativistic
eletrons diffusing upstream
of the shock wave. If the preshock electron scattering mean free path is
sufficiently long, observable
synchrotron halos outside the bulk of the radio emission can potentially
result; their absence can constrain
the mean free path from above. If scattering is primarily due, as expected, to
Alfven waves with amplitude
detla(B), the halo is expected to extend a distance of order r(sub
g)c(delta(B)/B)(exp 2)/v(sub s) beyond the
shock, where r(sub g) is the gyroradius of the electrons emitting at the
observed frequency, B is the
upstream magnetic field strength, v(sub s) is the shock velocity, and the
amplitude delta(B) refers to wave
with wavelength comparable to r(sub g), of order 10(exp 13) cm for typical
supernova-remnant parameters.
However, the detailed geometry of the halo varies with the assumptions about
particle acceleration in the
shock wave. I present an atlas of model profiles and images as a function of
preshock diffusion length, of
aspect angle between the magnetic field and the line of sight, and of other
relevant parameters.