Issue |
A&A
Volume 488, Number 1, September II 2008
|
|
---|---|---|
Page(s) | 417 - 428 | |
Section | Catalogs and data | |
DOI | https://doi.org/10.1051/0004-6361:200809571 | |
Published online | 24 June 2008 |
The XMM-Newton survey of the ELAIS-S1 field*
II. Optical identifications and multiwavelength catalogue of X-ray sources
1
INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Italy e-mail: chiara.feruglio@cea.fr
2
CEA, Irfu, Service d' Astrophysique, Centre de Saclay, 91191 Gif-sur-Yvette, France
3
Dipartimento di Fisica, Università Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
4
ASI Science Data Center, via G. Galilei, 00044 Frascati, Italy
5
INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
6
Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
7
Dip. di Astronomia, Universitá di Padova, Vicolo dell' Osservatorio 3, 35122 Padova, Italy
8
Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
9
INAF – Osservatorio Astronomico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
10
Dipartimento di Astronomia, Universitá di Bologna, via Ranzani 1, 40127 Bologna, Italy
Received:
13
February
2008
Accepted:
19
June
2008
We present the optical identifications and a multi-band catalogue of a sample of 478 X-ray sources detected in the XMM-Newton and Chandra surveys of the central 0.6 deg2 of the ELAIS-S1 field.
The most likely optical/infrared counterpart of each X-ray source was identified using the chance coincidence probability in the R and IRAC 3.6 μm bands.
This method was complemented by the precise positions obtained through Chandra observations.
We were able to associate a counterpart to each X-ray source in the catalogue.
Approximately 94% of them are detected in the R band, while
the remaining are blank fields in the optical down to ,
but have a near-infrared counterpart detected by IRAC within 6´´ from the XMM-Newton centroid.
The multi-band catalogue, produced using the positions of the identified optical counterparts, contains photometry in ten photometric bands, from B to the MIPS 24 μm band.
The spectroscopic follow-up allowed us to determine the redshift and classification for 237 sources (~
of the sample) brighter than
.
The spectroscopic redshifts were complemented by reliable photometric redshifts for 68 sources.
We classified 47% of the sources with spectroscopic redshift as broad-line active galactic nuclei (BL AGNs) with
, while sources without broad-lines (NOT BL AGNs) are about 46% of the spectroscopic sample and are found up to
.
The remaining fraction is represented by extended X-ray sources and stars.
We spectroscopically identified 11 type 2 QSOs among the sources with
> 8, with redshift between 0.9 and 2.6, high 2-10 keV luminosity (log
≥ 43.8 erg s-1) and hard X-ray colors suggesting large absorbing columns at the rest frame (log NH up to 23.6 cm-2).
BL AGNs show on average blue optical-to-near-infrared colors, softer X-ray colors and X-ray-to-optical colors typical of optically selected AGNs.
Conversely, narrow-line sources show redder optical colors, harder X-ray flux ratio and span a wider range of X-ray-to-optical colors.
On average the Spectral Energy Distributions (SEDs) of high-luminosity BL AGNs resemble the power-law typical of unobscured AGNs. The SEDs of NOT BL AGNs are dominated by the galaxy emission in the optical/near-infrared, and show a rise in the mid-infrared which suggests the presence of an obscured active nucleus.
We study the infrared-to-optical colors and near-infrared SEDs to infer the properties of the AGN host galaxies.
Key words: galaxies: active / surveys / X-rays: diffuse background / X-rays: galaxies / X-rays: general
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.