X-Ray Study of the Outer Region of Abell 2142 with Suzaku
Jun, 2011Citations per year
Abstract: (arXiv)
We observed outer regions of a bright cluster of galaxies A2142 with Suzaku. Temperature and brightness structures were measured out to the virial radius () with good sensitivity. We confirmed the temperature drop from 9 keV around the cluster center to about 3.5 keV at , with the density profile well approximated by the model with . Within 0.4\r_{200}, the entropy profile agrees with , as predicted by the accretion shock model. The entropy slope becomes flatter in the outer region and negative around . These features suggest that the intracluster medium in the outer region is out of thermal equilibrium. Since the relaxation timescale of electron-ion Coulomb collision is expected to be longer than the elapsed time after shock heating at , one plausible reason of the low entropy is the low electron temperature compared to that of ions. Other possible explanations would be gas clumpiness, turbulence and bulk motions of ICM\@. We also searched for a warm-hot intergalactic medium around and set an upper limit on the oxygen line intensity. Assuming a line-of-sight depth of 2 Mpc and oxygen abundance of 0.1 solar, the upper limit of an overdensity is calculated to be 280 or 380, depending on the foreground assumption.Note:
- 14 pages, 8 figures
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