2002MNRAS.331..417B -
Mon. Not. R. Astron. Soc., 331, 417-422 (2002/April-1)
The European Large Area ISO Survey - VII. ROSAT observations of ELAIS sources.
BASILAKOS S., GEORGANTOPOULOS I., PEREZ-FOURNON I., EFSTATHIOU A., ROWAN-ROBINSON M., CABRERA-GUERRA F., GONZALEZ-SOLARES E., ALEXANDER D.M., SERJEANT S. and OLIVER S.
Abstract (from CDS):
We present a cross-correlation between the European Large Area ISO Survey (ELAIS) 15-µm 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 Γ>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 (∼1012.98 h–2 L☉). Finally, one radio-loud QSO is the hardest X-ray source in our sample, presenting strong evidence for a high absorbing column (NH ∼ 1022 cm–2
Abstract Copyright:
2002 Blackwell Science Ltd
Journal keyword(s):
cosmology: observations - infrared: galaxies - X-rays: galaxies
Simbad objects:
15
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