Georgiana Ogrean, Marcus Bruggen, Huub Rottgering, Aurora Simionescu, Judith Croston, Reinout van Weeren, Matthias Hoeft
We present a study of the ICM of the galaxy cluster CIZA J2242.8+5301 using
deep XMM-Newton observations. The cluster hosts an extremely elongated (2 Mpc),
narrow (~50 kpc) radio relic that has been nicknamed the "Sausage".
Additionally, a counter-relic is also present, along with a faint, extended
radio halo. We have searched for evidence of shock fronts in the surface
brightness, temperature, density, and pressure, and we studied the cluster
morphology using power ratios. The surface brightness profiles to the north and
south of the centre are almost identical in shape. This symmetry supports the
hypothesis that the two merging clusters have almost equal masses and a small
impact parameter. The ICM on the inner side of the relics (the side towards the
cluster centre), has a relatively low temperature of ~5 keV and only jumps to
temperatures >10 keV after about 500 kpc. The jumps in temperature and pressure
coincide with two symmetric "bumps" in the X-ray surface brightness profiles.
We discuss possible causes for this. The inner shocks do not cause detectable
radio relics. Surprisingly, the temperatures and pressures determined from the
spectral fits depend strongly on the assumed abundance table and the absorption
model. We speculate that this is characteristic of all clusters at low Galactic
latitudes.
View original:
http://arxiv.org/abs/1201.1502
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