A New Cluster of Galaxies towards the Galactic Bulge, Suzaku J1759-3450
Abstract
We observed an extended X-ray source designated as Suzaku J1759-3450 with the Suzaku and Chandra observations towards 1RXS J175911.0-344921, which is an unidentified X-ray source listed in the ROSAT Bright Source Catalogue. A conspicuous emission line at 6 keV was also found in the Suzaku J1759-3450 spectrum. Assuming the emission line to be K emission from He-like Fe ions, we inferred Suzaku J1759-3450 to be an extragalactic object located at z = 0.13. The radial profile of the surface brightness in the 0.5-10 keV band was explained well with an isothermal beta-model of rc = 1.61' and beta = 0.78. The X-ray spectrum was well reproduced by an optically-thin thermal plasma with the electron temperature of kTe = 5.3 keV attenuated by the photoelectric absorption of NH = 2.3 x 1021 cm-2. The bolometric X-ray luminosity of LX (r < r500) = 4.3 x 1044 erg s-1 is consistent with that expected from the LX-T relation of clusters of galaxies. In terms of the spatial extent, the X-ray spectrum, and the bolometric luminosity of the X-ray emitting gas, we concluded that Suzaku J1759-3450 is a new cluster of galaxies.