NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-24 T01:14:50 PDT
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For refcode 2014A&A...569A..71C:
Retrieve 85 NED objects in this reference.
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2014A&A...569A..71C Searching for highly obscured AGNs in the XMM-Newton serendipitous source catalog Corral, A.; Georgantopoulos, I.; Watson, M. G.; Rosen, S. R.; Koulouridis, E.; Page, K. L.; Ranalli, P.; Lanzuisi, G.; Mountrichas, G.; Akylas, A.; Stewart, G. C.; Pye, J. P. Abstract. The majority of active galactic nuclei (AGNs) are obscured by large amounts of absorbing material that makes them invisible at many wavelengths. X-rays, given their penetrating power, provide the most secure way for finding these AGNs. The XMM-Newton serendipitous source catalog, of which 3XMM-DR4 is the latest version, is the largest catalog of X-ray sources ever produced; it contains about half a million detections. These sources are mostly AGNs. We have derived X-ray spectral fits for very many 3XMM-DR4 sources (>~114 000 observations, corresponding to ~77 000 unique sources), which contain more than 50 source photons per detector. Here, we use a subsample of ~=1000 AGNs in the footprint of the SDSS area (covering 120 deg^2^) with available spectroscopic redshifts. We searched for highly obscured AGNs by applying an automated selection technique based on X-ray spectral analysis that is capable of efficiently selecting AGNs. The selection is based on the presence of either a) flat rest-frame spectra from a simple power-law fit; b) flat observed spectra from an absorbed power-law fit; c) an absorption turnover, indicative of a high rest-frame column density; or d) the presence of an Fe Kalpha line with a large equivalent width (>500 eV). We found 81 highly obscured candidate sources. Subsequent detailed manual spectral fits revealed that 28 of them are heavily absorbed by column densities higher than 10^23^ cm^-2^. Of these 28 AGNs, 15 are candidate Compton-thick AGNs on the basis of either a high column density, consistent within the 90% confidence level with N_H_> 10^24^ cm^-2^, or a large equivalent width (>500 eV) of the Fe Kalpha line. Another six are associated with near-Compton-thick AGNs with column densities of ~ 5 x 10^23^ cm^-2^. A combination of selection criteria a) and c) for low-quality spectra, and a) and d) for medium- to high-quality spectra, pinpoint highly absorbed AGNs with an efficiency of 80%. Table 4 is available in electronic form at http://www.aanda.org Key words: X-rays: general, X-rays: diffuse background, surveys, galaxies: active
Retrieve 85 NED objects in this reference.
Please click here for ADS abstract

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