XMM-Newton Observation of the Cluster of Galaxies Abell 1650
  We present the nonuniform distribution of temperature and abundance in the angular extent of 10'(1.4 Mpc) in A1650 observed by XMM-Newton. Spectral analysis was carried out in 19 systematically-subdivided regions, and in 15 specified regions referred to the hardness ratio (HR) map. The value of HR, defined as the ratio of counts in the 1.6-10 keV band to those in the 0.8-1.6 keV, is an indicator to investigate the spatial variation of spectral features. The temperature and abundance were obtained to be 4-6 keV and 0.2-0.5 solar value with average values of 5.62+0.05-0.07 keV and 0.36+0.02-0.01 solar value within a radius of 5', respectively. The redshift was derived to be 8.01+0.02-0.02x10^-2 against an optical value of 8.45x10^-2. It turned out that cool regions with a temperature of around 4 keV and a scalelength of a few 100 kpc are patchily distributed in the outer envelope. This temperature structure could be explained by the infalling of groups of galaxies into the cluster main body. More than 30 point sources were found around A1650 in the FOV of 30'. The spectrum of the Galactic diffuse emission was obtained in the outskirts of A1650. 
Seiji Takahashi and Koujun Yamashita (Nagoya University)