Detection of a radio bridge in Abell 3667
  We have detected a radio bridge of unpolarized synchrotron emission
connecting the NW relic of the galaxy cluster Abell 3667 to its central
regions. We used data at 2.3 GHz from the S-band Polarization All Sky Survey
(S-PASS) and at 3.3 GHz from a follow up observation, both conducted with the
Parkes Radio Telescope. This emission is further aligned with a diffuse X-ray
tail, and represents the most compelling evidence for an association between
intracluster medium turbulence and diffuse synchrotron emission. This is the
first clear detection of a bridge associated both with an outlying cluster
relic and X-ray diffuse emission. All the indicators point toward the
synchrotron bridge being related to the post-shock turbulent wake trailing the
shock front generated by a major merger in a massive cluster. Although
predicted by simulations, this is the first time such emission is detected with
high significance and clearly associated with the path of a confirmed shock.
Although the origin of the relativistic electrons is still unknown, the
turbulent re-acceleration model provides a natural explanation for the
large-scale emission. The equipartition magnetic field intensity of the bridge
is B_eq = 2.2 +/- 0.3 \mu G. We further detect diffuse emission coincident with
the central regions of the cluster for the first time.
