Non-thermal radio supernova remnants of exiled Wolf-Rayet stars
  A signification fraction of Galactic massive stars (> 8Mo) are ejected from
their parent cluster and supersonically sail away through the interstellar
medium (ISM). The winds of these fast-moving stars blow asymmetric bubbles thus
creating a circumstellar environment in which stars eventually die with a
supernova explosion. The morphology of the resulting remnant is largely
governed by the circumstellar medium of the defunct progenitor star. In this
paper, we present 2D magneto-hydrodynamical simulations investigating the
effect of the ISM magnetic field on the shape of the supernova remnants of a
35Mo star evolving through a Wolf-Rayet phase and running with velocity 20 and
40 km/s, respectively. A 7 microG ambient magnetic field is sufficient to
modify the properties of the expanding supernova shock front and in particular
to prevent the formation of filamentary structures. Prior to the supernova
explosion, the compressed magnetic field in the circumstellar medium stabilises
the wind/ISM contact discontinuity in the tail of the wind bubble. A
consequence is a reduced mixing efficiency of ejecta and wind materials in the
inner region of the remnant, where the supernova shock wave propagates.
Radiative transfer calculations for synchrotron emission reveal that the
non-thermal radio emission has characteristic features reflecting the asymmetry
of exiled core-collapse supernova remnants from Wolf-Rayet progenitors. Our
models are qualitatively consistent with the radio appearance of several
remnants of high-mass progenitors, namely the bilateral G296.5+10.0 and the
shell-type remnants CTB109 and Kes 17, respectively.
