X-Ray Study of the Outer Region of Abell 2142 with Suzaku

H. Akamatsu; A. Hoshino; Y. Ishisaki; T. Ohashi; K. Sato; Y. Takei; N. Ota

doi:10.1093/pasj/63.sp3.S1019

paper

X-Ray Study of the Outer Region of Abell 2142 with Suzaku

arXiv:1106.5653 · doi:10.1093/pasj/63.sp3.S1019

Abstract

We observed outer regions of a bright cluster of galaxies A2142 with Suzaku. Temperature and brightness structures were measured out to the virial radius ( $r_{200}$ ) with good sensitivity. We confirmed the temperature drop from 9 keV around the cluster center to about 3.5 keV at $r_{200}$ , with the density profile well approximated by the $β$ model with $β = 0.85$ . Within $0.4\r_{200}$, the entropy profile agrees with $r^{1.1}$ , as predicted by the accretion shock model. The entropy slope becomes flatter in the outer region and negative around $r_{200}$ . 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 $r_{200}$ , 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 $r_{200}$ 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.

14 pages, 8 figures

X-Ray Study of the Outer Region of Abell 2142 with Suzaku

Abstract

References in corpus (12)

Cited by in corpus (68)