The deep XMM-Newton Survey of M 31 (Stiele et al.)
- Published on 30 September 2011
In section 14. Catalogs and data
The deep XMM-Newton Survey of M 31
The Andromeda galaxy has been entirely surveyed in X-ray with XMM, giving rise to a catalog of nearly 2000 X-ray sources (between 0.2 and 12 keV), of which half are new. Source classification and identification were based on X-ray hardness ratios, variability, the spatial extent of the sources, and cross correlation with catalogs in the X-ray, optical, infrared, and radio wavelengths. The classification has unveiled supersoft sources, such as optical novae, which are supernova remnants that lie within the 10kpc star-forming ring, and are probably type II supernovae. The brightest sources belong to the class of X-ray binaries, and they were identified either by their temporal variability or through their correlations with globular clusters. Possible high-mass binary candidates were selected from optical and X-ray color-color diagrams. Two of these candidates have the X-ray spectrum expected for a neutron star primary. Nevertheless, 65% of the sources cannot be classified: they are either X-ray binaries, Crab-like supernova remnants, or X-ray sources in the background.