Detection of a radio bridge in Abell 3667
Abstract
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 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 towards 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 Beq = 2.2 ± 0.3 μG. We further detect diffuse emission coincident with the central regions of the cluster for the first time.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2013
- DOI:
- 10.1093/mnras/stt002
- arXiv:
- arXiv:1205.1082
- Bibcode:
- 2013MNRAS.430.1414C
- Keywords:
-
- acceleration of particles;
- polarization;
- radiation mechanisms: non-thermal;
- shock waves;
- galaxies: clusters: general;
- galaxies: clusters: individual: A3667;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 10 pages, 16 figures, accepted for publication on MNRAS. Replaced with the version accepted for publication: also the 3.3 GHz image cleaned from compact sources