Searching for absorbed AGN in the 2XMM-Newton pre-release EPIC Serendipitous Source Catalogue ^*

¹ INAF – Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy e-mail: elisabetta.memola@brera.inaf.it
² Department of Physics & Astronomy, University of Leicester, Leicester LE1 7RH, UK
³ AIP – Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany

Received: 14 October 2006
Accepted: 29 December 2006

Abstract

Aims.We aim to test a method of efficiently selecting X-ray obscured AGN in the 2XMM-Newton EPIC Serendipitous Source Catalogue.

Methods.By means of a strong correlation established using the XMM-Newton Hard Bright Sample between the intrinsic absorption and the hardness ratio to the 0.5–2.0 keV and 2.0–4.5 keV bands, an efficient way of selecting absorbed sources has been worked out. A hardness ratio selection based on the 2XMM-Newton pre-release Source Catalogue led us to the definition of candidates likely to be obscured in X-rays.

Results.X-ray and optical spectral analysis were performed for three objects. Strong absorption ( cm^-2) was detected from the X-ray analysis, confirming the efficiency of the method used to select obscured sources. The presence of absorption is also revealed in the optical band, although at a significantly lower level than inferred from the X-ray band.