* Astronomy

Title: Suzaku and Chandra Observations of CIZA J1700.8-3144, a Cluster of Galaxies in the Zone of Avoidance
Author: Hideyuki Mori, Yo****omo Maeda, Yoshihiro Ueda, Kazuhiro Nakazawa, Yuzuru Tawara

We present the Chandra and Suzaku observations of 1RXS J170047.8-314442, located towards the Galactic bulge, to reveal a wide-band (0.3-10 keV) X-ray morphology and spectrum of this source. With the Chandra observation, no point source was found at the position of 1RXS J170047.8-314442. Alternatively, we revealed the presence of diffuse X-ray emission by the wide-band X-ray image obtained from the Suzaku XIS. Although the X-ray emission had a nearly circular shape with a spatial extent of ~3.5', the surface brightness profile was not axisymmetric; a bright spot-like emission was found at ~1' away in the north-western direction from the center. The radial profile of the surface brightness, except for this spot-like emission, was reproduced with a single B-model; B and the core radius were found to be 1.02 and 1.51', respectively. The X-ray spectrum of the diffuse emission showed an emission line at ~6 keV, indicating an origin of a thermal plasma. The spectrum was well explained with an absorbed optically-thin thermal plasma model with a temperature of 6.2 keV and a redshift parameter of z=0.14±0.01. Hence, the X-ray emission was considered to arise from the hot gas associated with a cluster of galaxies. Our spectroscopic result confirmed the optical identification of 1RXS J170047.8-314442 by Kocevski et al. (2007): CIZA J1700.8-3144, a member of the cluster catalogue in the Zone of Avoidance. The estimated bolometric X-ray luminosity of 5.9 x 10^44 erg s^-1 was among the lowest with this temperature, suggesting that this cluster is far from relaxed.

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