Thermodynamics of the Coma Cluster Outskirts. (arXiv:1302.4140v1 [astro-ph.CO])

Thermodynamics of the Coma Cluster Outskirts. (arXiv:1302.4140v1 [astro-ph.CO]):
We present results from a large mosaic of Suzaku observations of the Coma
Cluster, focusing on the thermodynamic properties of the ICM on large scales.
The measured temperature and X-ray brightness profiles are similar along four
relatively undisturbed azimuths probed, with the temperature decreasing from
~8.5 keV at the cluster center to ~2 keV at 2 Mpc. The SW merger boosts the
surface brightness, allowing us to detect X-ray emission out to 2.5 Mpc along
this fifth direction. The X-ray image also reveals two arc-shaped regions with
excess surface brightness towards the east and west of the main cluster core.
These regions appear over-pressured and most likely originate from merger
induced large scale supersonic gas motions. The azimuthally averaged
temperature profile, as well as the deprojected density and pressure profiles
towards the E and NW, all show a sharp drop consistent with an outward
propagating shock front located at the outermost edge of the giant radio halo
observed at 352 MHz with the WSRT and which may be powering this radio
emission. The shape of the entropy profiles along the relatively relaxed E and
NW directions at large radii is consistent with the average profiles of
evolved, well formed cool core clusters, suggesting similar accretion
histories. Our data indicate a flat metal abundance profile at about 0.3 of the
Solar value out to almost the virial radius of Coma, which would favor galactic
winds over ram-pressure stripping as the dominant enrichment mechanism in the
ICM.