J/ApJ/693/1713 Spectroscopy of X-ray sources in ECDF-S (Treister+, 2009)
Optical spectroscopy of X-ray sources in the extended Chandra Deep Field South.
Treister E., Virani S., Gawiser E., Urry C.M., Lira P., Francke H.,
Blanc G.A., Cardamone C.N., Damen M., Taylor E.N., Schawinski K.
<Astrophys. J., 693, 1713-1727 (2009)>
=2009ApJ...693.1713T 2009ApJ...693.1713T
ADC_Keywords: Active gal. nuclei ; Redshifts ; Spectroscopy ; X-ray sources ;
Galaxies, optical ; Surveys
Keywords: galaxies: active - quasars: general - X-rays: galaxies
Abstract:
We present the first results of our optical spectroscopy program aimed
to provide redshifts and identifications for the X-ray sources in the
Extended Chandra Deep Field South. A total of 339 sources were
targeted using the IMACS spectrograph at the Magellan telescopes and
the VIMOS spectrograph at the VLT. We measured redshifts for 186 X-ray
sources, including archival data and a literature search. We find that
the active galactic nucleus (AGN) host galaxies have on average redder
rest-frame optical colors than nonactive galaxies, and that they live
mostly in the "green valley". The dependence of the fraction of AGNs
that are obscured on both luminosity and redshift is confirmed at high
significance and the observed AGN spatial density is compared with the
expectations from existing luminosity functions. These AGNs show a
significant difference in the mid-IR to X-ray flux ratio for obscured
and unobscured AGNs, which can be explained by the effects of dust
self-absorption on the former. This difference is larger for lower
luminosity sources, which is consistent with the dust opening angle
depending on AGN luminosity.
Description:
Sources targeted for spectroscopy were selected from the catalog of
Chandra sources of Virani et al. (2006, Cat. J/AJ/131/2373). We used
the IMACS wide-field spectrograph mounted on the Magellan I Baade
telescope at Las Campanas Observatory in 2003 Oct 26-27, 2005 Feb 4-7,
2005 Nov 2-3, 2006 Oct 25-27, 2006 Nov 21-22 and 2007 Feb 18-20. The
VIMOS spectrograph mounted at the Nasmyth focus B of UT3 was also used
to obtain optical spectroscopy for the X-ray sources in the ECDF-S.
In order to take advantage of existing spectroscopic observations of
the X-ray sources in ECDF-S, we did an extensive literature search. In
particular, we used the Master Compilation of GOODS/CDF-S spectroscopy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 107 339 X-ray, optical and mid-IR properties of the
X-ray sources in the ECDF-S
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See also:
III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005)
J/ApJS/191/124 : Optical spectroscopy of X-ray sources (Silverman+, 2010)
J/A+A/512/A12 : VLT/VIMOS spectroscopy in GOODS-South field (Balestra+, 2010)
J/A+A/478/83 : GOODS-South Field VLT/FORS2 redshifts. III. (Vanzella+, 2008)
J/A+A/454/423 : GOODS-South Field VLT/FORS2 redshifts. II. (Vanzella+, 2006)
J/AJ/131/2373 : Extended Chandra Deep Field-South survey (Virani+, 2006)
J/ApJ/640/603 : Catalog of AGNs in the GOODS fields (Treister+, 2006)
J/A+A/434/53 : GOODS-South Field redshifts (Vanzella+, 2005)
J/A+A/428/1043 : Redshifts from VIMOS VLT Deep Survey (Le Fevre+, 2004)
J/ApJS/155/271 : Chandra Deep Field-South: Optical spectroscopy (Szokoly+,
2004)
J/MNRAS/328/150 : KX redshift survey (Croom+, 2001)
http://www.eso.org/sci/activities/garching/projects/goods/MasterSpectroscopy :
Compilation of GOODS/CDF-S spectroscopy catalogs
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID X-ray identification number (1)
5- 13 E9.3 mW/m2 Fsoft Soft X-ray (0.5-2keV) flux (in erg/cm2/s/)
15- 23 E9.3 mW/m2 Fhard Hard X-ray (2-8keV) flux (in erg/cm2/s/)
25- 30 F6.3 --- HR Hardness ratio
32- 36 F5.3 --- E_HR Upper error in HR
38- 42 F5.3 --- e_HR Lower error in HR
44- 48 F5.3 --- zsp ?=9.99 Spectroscopic redshift
50- 54 A5 --- r_zsp Source of spectrum (2)
56- 59 A4 --- Class Optical classification (3)
61- 66 F6.3 [10-7W] Lhard ? Log of hard X-ray (2-8keV) luminosity
68- 74 F7.2 mJy F24um ? 24 micron flux
76- 80 F5.2 mJy e_F24um ? Error in Flux-24
82 A1 --- r_F24um Source of 24 microns photometry (4)
84- 88 F5.3 --- Gamma ? Γ, slope of the power law
90- 94 F5.3 --- E_Gamma ? Upper error in Gamma
96-100 F5.3 --- e_Gamma ? Lower error in Gamma
102-107 F6.3 [cm-2] logNH ? Log of neutral hydrogen (HI) column density
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Note (1): From the catalog of Virani et al. (2006, Cat. J/AJ/131/2373,
<[VTU2006] NNN> in Simbad).
Note (2): Sources are
* BERG (VIMOS observations on the ESO archive, program of
Bergeron et al. (program ID 072.A-0139)), or
* FORS2, IMACS, SZOK (Szokoly et al., 2004, Cat.J/ApJS/155/271),
* VIMOS or VVDS (Le Fevre et al., 2005, Cat. III/250).
Note (3): Class as follows:
UNK = unknown;
OAGN = obscured AGN;
UAGN = Unobscured AGN;
ELG = Emission line galaxy;
ALG = Absorption line galaxy;
STAR = star.
Note (4): Sources of photometry:
* F = FIDEL (reduced images available at
http://data.spitzer.caltech.edu/popular/fidel/20070917_enhanced);
* G = GOODS.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 29-Nov-2010