E. Carretti, S. Brown, L. Staveley-Smith, J. M. Malarecki, G. Bernardi, B. M. Gaensler, M. Haverkorn, M. J. Kesteven, S. Poppi
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 bridge, and represents the most compelling direct 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 an X-ray bridge. We conclude that the synchrotron bridge is related to the post-shock turbulence wake trailing a shock front. 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 bridge magnetic field intensity is 0.5-0.6 uG. We further detect diffuse emission coincident with the central regions of the cluster for the first time.
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http://arxiv.org/abs/1205.1082
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