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arXiv · 1004.2331

XMM-Newton Observation of the Northwest Radio Relic Region in Abell 3667

A. Finoguenov·C. L. Sarazin·K. Nakazawa·D. R. Wik·T. E. Clarke
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Abstract

Abell 3667 is the archetype of a merging cluster with radio relics. The NW radio relic is the brightest cluster relic or halo known, and is believed to be due to a strong merger shock. We have observed the NW relic for 40 ksec of net XMM time. We observe a global decline of temperature across the relic from 6 to 1 keV, similar to the Suzaku results. Our new observations reveal a sharp change of both temperature and surface brightness near the position of the relic. The increased X-ray emission on the relic can be equivalently well described by either a thermal or nonthermal spectral model. The parameters of the thermal model are consistent with a Mach number M~2 shock and a shock speed of ~1200 km s^-1. The energy content of the relativistic particles in the radio relic can be explained if they are (re)-accelerated by the shock with an efficiency of ~0.2%. Comparing the limit on the inverse Compton X-ray emission with the measured radio synchrotron emission, we set a lower limit to the magnetic field in the relic of 3 muG. If the emission from the relic is non-thermal, this lower limit is in fact the required magnetic field.

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A. Finoguenov, C. L. Sarazin, K. Nakazawa, D. R. Wik, T. E. Clarke. 2010-04-14. XMM-Newton Observation of the Northwest Radio Relic Region in Abell 3667. https://doi.org/10.1088/0004-637x%2F715%2F2%2F1143

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