Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-11-12
Astrophys.J. 621 (2005) 104-122
Astronomy and Astrophysics
Astrophysics
47 pages, 19 figures, Astrophysical Journal Accepted
Scientific paper
10.1086/427471
We present the first results from the Cal\'an-Yale Deep Extragalactic Research (CYDER) survey. The main goal of this survey is to study serendipitous X-ray sources detected by Chandra in an intermediate flux range ($10^{-15}-10^{-12}$ ergs s$^{-1}$) that comprises most of the X-ray background. 267 X-ray sources spread over 5 archived fields were detected. The $\log N-\log S$ distribution obtained for this sample is consistent with the results of other surveys. Deep $V$ and $I$ images were taken of these fields in order to calculate X-ray-to-optical flux ratios. Identifications and redshifts were obtained for 106 sources using optical spectroscopy from 8-m class telescopes to reach the optically faintest sources, to the same level as deeper X-ray fields like the Chandra Deep Fields, showing that the nature of sources detected depends mostly on the optical limit for spectroscopy. In general, sources optically classified as obscured Active Galactic Nuclei (AGNs) have redder optical colors than unobscured AGN. A rough correlation between $f_X/f_{\rm opt}$ and hard X-ray luminosity was found for obscured AGN confirming the prediction by existing models that in obscured AGN the optical light is completely dominated by the host galaxy. The previously claimed decrease of the obscured to unobscured AGN ratio with increasing X-ray luminosity is observed. However, this correlation can be explained as a selection effect caused by the lower optical flux of obscured AGN. Comparison between the observed $N_H$ distribution and predictions by existing models shows that the sample appears complete up to $N_H<3\times 10^{22}$ cm$^{-2}$, while for more obscured sources incompleteness plays an important role in the observed obscured to unobscured AGN ratio.
Castander Francisco
Coppi Paolo
Gawiser Eric
Gonzalez Valentino
Herrera David
No associations
LandOfFree
The Calan-Yale Deep Extragalactic Research (CYDER) Survey: Optical Properties and Deep Spectroscopy of Serendipitous X-ray Sources does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Calan-Yale Deep Extragalactic Research (CYDER) Survey: Optical Properties and Deep Spectroscopy of Serendipitous X-ray Sources, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Calan-Yale Deep Extragalactic Research (CYDER) Survey: Optical Properties and Deep Spectroscopy of Serendipitous X-ray Sources will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-86681