XMM-Newton observations of the M31 northern disk: Properties of selected   X-ray sources and diffuse emission
  We present the results of XMM-Newton survey of the northern part of the disk of M31. The results of a spectral and timing analysis of the thirty seven brightest sources are presented. Combining the results of X-ray analysis with available data at other wavelengths, we were able to classify ~50%, or 19 out of 37 sources. Two sources in our sample were previously unknown: the hard X-ray source XMMU J004415.8+413057 and a transient supersoft source XMMUJ004414.1+412206. We report the discovery of possible X-ray pulsations from the source XMMUJ004415.8+413057 with a period of 197 s. The spectral and timing properties of XMMU J004415.8+413057 make it first accreting X-ray pulsar candidate detected in M31. We report on the first unambiguous detection of the soft unresolved X-ray emission from the disk of M31. The unresolved emission follows the pattern of the spiral arms and can be traced up to distance of ~0.5 deg (~7 kpc at 760 kpc) from the center of the galaxy. The spectrum of the unresolved emission shows dominant soft thermal component which can be fitted with a ~0.3 keV optically thin thermal plasma emission models. We suggest that significant part of this diffuse soft X-ray component may represent hot diffuse gas in the spiral arms of M31 and emission from normal stars in the disk of M31. 
S. Trudolyubov, O. Kotov, W. Priedhorsky, F. Cordova, K. Mason