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Title: Detection of a radio bridge in Abell 3667
Authors: 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 unpolarised 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 Polarisation 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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Title: Properties of the intracluster medium of Abell 3667 observed with Suzaku XIS
Authors: H. Akamatsu, J. de Plaa, J. Kaastra, Y. Ishisaki, T. Ohashi, M. Kawaharada, K. Nakazawa

We observed the northwest region of the cluster of galaxies A3667 with the Suzaku XIS instrument. The temperature and surface brightness of the intracluster medium were measured up to the virial radius (r200-2.3 Mpc). The radial temperature profile is flatter than the average profile for other clusters until the radius reaches the northwest radio relic. The temperature drops sharply from 5 keV to about 2 keV at the northwest radio relic region. The sharp changes of the temperature can be interpreted as a shock with a Mach number of about 2.5. The entropy slope becomes flatter in the outer region and negative around the radio relic region. In this region, the relaxation timescale of electron-ion Coulomb collisions is longer than the time elapsed after the shock heating and the plasma may be out of equilibrium. Using differential emission measure (DEM) models, we also confirm the multi-temperature structure around the radio relic region, characterised by two peaks at 1 keV and 4 keV. These features suggest that the gas is heated by a shock propagating from the center to outer region.

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