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|Title:||The central region of M 31 observed with XMM-Newton. I. Group properties and diffuse emission|
Osborne, J. P.
Watson, M. G.
West, R. G.
La Palombara N
Read, A. M.
|Publisher:||EDP Sciences for European Southern Observatory (ESO)|
|Citation:||Astronomy & Astrophysics, 2001, 365 (1)|
|Abstract:||We present the results of a study based on an XMM-Newton Performance Verification observation of the central 30´of the nearby spiral galaxy M 31. In the 34-ks European Photon Imaging Camera (EPIC) exposure, we detect 116 sources down to a limiting luminosity of #1 10#2 erg s-1 (0.3-12 keV, d=760 kpc). The luminosity distribution of the sources detected with XMM-Newton flattens at luminosities below $\sim$ 2.5 1037 erg s-1 . We make use of hardness ratios for the detected sources in order to distinguish between classes of objects such as super-soft sources and intrinsically hard or highly absorbed sources. We demonstrate that the spectrum of the unresolved emission in the bulge of M 31 contains a soft excess which can be fitted with a $\sim$0.35-keV optically-thin thermal-plasma component clearly distinct from the composite point-source spectrum. We suggest that this may represent diffuse gas in the centre of M 31, and we illustrate its extent in a wavelet-deconvolved image.|
|Rights:||Copyright © 2001 ESO. Reproduced with permission from Astronomy & Astrophysics, © ESO.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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