2004MNRAS.349..135G -
Mon. Not. R. Astron. Soc., 349, 135-145 (2004/March-3)
The XMM-Newton/2dF survey - II. The nature of X-ray-faint optically bright X-ray sources.
GEORGAKAKIS A., GEORGANTOPOULOS I., VALLBE M., KOLOKOTRONIS V., BASILAKOS S., PLIONIS M., STEWART G.C., SHANKS T. and BOYLE B.J.
Abstract (from CDS):
In this paper we investigate the properties of low X-ray-to-optical flux ratio sources detected in a wide-area (2.5 deg2) shallow [fX(0.5-8 keV) ~ 10–14 erg/s/cm2 ] XMM-Newton survey. We find a total of 26 sources (5 per cent of the total X-ray-selected population) with log fX/fopt< -0.9 to the above flux limit. Optical spectroscopy is available for 20 of these low X-ray-to-optical flux ratio objects. Most of them are found to be associated with Galactic stars (a total of eight) and broad-line active galactic nuclei (AGNs; a total of eight). We also find two sources with optical spectra showing absorption and/or narrow emission lines and X-ray/optical properties suggesting AGN activity. Another two sources are found to be associated with low-redshift galaxies with narrow emission-line optical spectra, X-ray luminosities LX(0.5-8 keV) ~ 1041 erg/s and log fX/fopt~-2 suggesting `normal' star-forming galaxies. Despite the small-number statistics the sky density of `normal' X-ray-selected star-forming galaxies at the flux limit of the present sample is low, consistent with previous ROSAT High-Resolution Imager (HRI) deep surveys. Also, the number density estimated here is in good agreement with both the log N -log S of `normal' galaxies in the Chandra Deep Field North (extrapolated to bright fluxes) and model predictions based on the X-ray luminosity function of local star-forming galaxies.
Abstract Copyright:
2004 RAS
Journal keyword(s):
surveys - X-rays: galaxies - X-rays: general
VizieR on-line data:
<Available at CDS (J/MNRAS/349/135): table1.dat>
Nomenclature:
Table 1: XMM2DF JHHMMSS.ss+DDMMSS.ss N=4.
CDS comments:
Table 1: numbering 'NN' in first col. is not used in SIMBAD.
Simbad objects:
28
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2004MNRAS.349..135G and select 'bookmark this link' or equivalent in the popup menu