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The XMM-Newton Wide Angle Survey (XWAS)

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posted on 16.12.2016, 11:29 by P. Esquej, M. Page, F. J. Carrera, S. Mateos, J. Tedds, M. G. Watson, A. Corral, J. Ebrero, M. Krumpe, S. R. Rosen, M. T. Ceballos, A. Schwope, C. G. Page, A. Alonso-Herrero, A. Caccianiga, R. Della Ceca, O. Gonzalez-Martin, G. Lamer, P. Severgnini
Aims. This programme is aimed at obtaining one of the largest X-ray selected samples of identified active galactic nuclei to date in order to characterise such a population at intermediate fluxes, where most of the Universe’s accretion power originates. We present the XMM-Newton Wide Angle Survey (XWAS), a new catalogue of almost a thousand X-ray sources spectroscopically identified through optical observations. Methods. A sample of X-ray sources detected in 68 XMM-Newton pointed observations was selected for optical multi-fibre spectroscopy. Optical counterparts and corresponding photometry of the X-ray sources were obtained from the SuperCOSMOS Sky Survey. Candidates for spectroscopy were initially selected with magnitudes down to R ∼ 21, with preference for X-ray sources having a flux F0.5−4.5 keV ≥ 10−14 erg s−1 cm−2. Optical spectroscopic observations were made using the Two Degree Field of the Anglo Australian Telescope, and the resulting spectra were classified based on optical emission lines. Results. We have identified through optical spectroscopy 940 X-ray sources over Ω ∼ 11.8 deg2 of the sky. Source populations in our sample can be summarised as 65% broad line active galactic nuclei (BLAGN), 16% narrow emission line galaxies (NELGs), 6% absorption line galaxies (ALGs) and 13% stars. An active nucleus is also likely to be present in the large majority of the X-ray sources spectroscopically classified as NELGs or ALGs. Sources lie in high-galactic latitude (|b| > 20 deg) XMM-Newton fields mainly in the southern hemisphere. Owing to the large parameter space in redshift (0 ≤ z ≤ 4.25) and flux (10−15 ≤ F0.5−4.5 keV ≤ 10−12 erg s−1 cm−2) covered by the XWAS this work provides an excellent resource for the further study of subsamples and particular cases. The overall properties of the extragalactic objects are presented in this paper. These include the redshift and luminosity distributions, optical and X-ray colours and X-ray-to-optical flux ratios.


XMM-Newton project is an ESA science mission with instruments and contributions directly funded by ESA member states and NASA. This project is based on data obtained with the 2dF multi-fibre spectrograph of the Anglo Australian Telescope. PE and AAH acknowledge support from the Spanish Plan Nacional de Astronomía y Astrofísica under grant AYA2009- 05705-E. P.E., M.P., S.M., M.W. and J.A.T. acknowledge support from the UK STFC research council. This work has been supported in part by the German DLR under contract numbers 50 OR 0404 and 50 OX 0201. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (/FP7/2007-2013/) under grant agreement No 229517. M.K. acknowledges the support of the Deutsches Zentrum für Luftund Raumfahrt (DLR) GmbH under contract No. FKZ 50 OR 0404. The Space Research Organisation of The Netherlands is supported financially by NWO, the Netherlands Organisation for Scientific Research. A.C., R.D.C. and P.S. acknowledge financial support from ASI (grant n. I/088/06/0, COFIS contract and grant n. I 009/10/0).



Astronomy and Astrophysics, 557, A123 (2013)

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/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/School of Medicine/Department of Health Sciences


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Astronomy and Astrophysics


EDP Sciences for European Southern Observatory (ESO), Springer Verlag (Germany) [Former Publisher]





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Reduced spectra (FITS files) are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr ( or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/557/A123