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The European Large Area ISO Survey - VII. ROSAT observations of ELAIS sources

Basilakos, S.; Georgantopoulos, I.; Pérez-Fournon, I.; Efstathiou, A.; Rowan-Robinson, M.; Cabrera-Guerra, F.; González-Solares, E.; Alexander, D.M.; Serjeant, S. and Oliver, S. (2002). The European Large Area ISO Survey - VII. ROSAT observations of ELAIS sources. Monthly Notices of the Royal Astronomical Society, 331(2) pp. 417–422.

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We present a cross-correlation between the European Large Area ISO Survey (ELAIS) 15-mum ISO survey with the ROSAT (0.1-2keV) all-sky survey and the pointed observations WGACAT source catalogue. The resulting sample contains 15 objects. Optical spectroscopic identifications exist for 13 objects: six broad-line quasi-stellar objects (QSOs), four narrow-line galaxies (NLGs) or type 2 active galactic nuclei (AGN) and three stars. We have used both the X-ray to infrared (IR) luminosity flux ratio fx/fIR and the X-ray hardness ratios diagnostics to estimate the amount of obscuration in these objects. The X-ray spectrum of the narrow-line galaxies does not present strong evidence for obscuration; however, the low fx/fIR ratio combined with the high X-ray luminosities suggest that at least one of the NLGs is associated with an obscured Seyfert nucleus. Four out of the six QSOs present high fx/fIR ratios and steep X-ray spectra with Gamma>2. One QSO (ELAISC15-J133442+375736) at a redshift of z=1.89, has an abnormally low X-ray/IR flux ratio, with its infrared luminosity approaching that of an hyperluminous galaxy (~1012.98h-2Lsolar). Finally, one radio-loud QSO is the hardest X-ray source in our sample, presenting strong evidence for a high absorbing column (NH~1022cm-2).

Item Type: Journal Item
ISSN: 1365-2966
Extra Information: Some of the symbols may not have transferred correctly into this bibliographic record and/or abstract.
Keywords: cosmology; observations; infrared; galaxies; X-rays
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Space
Item ID: 5805
Depositing User: Users 13 not found.
Date Deposited: 06 Nov 2006
Last Modified: 02 May 2018 12:40
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