J/ApJ/680/130 Mid-IR colors of AGNs in the MUSYC ECDF-S (Cardamone+, 2008)
Mid-infrared properties and color selection for X-Ray-detected active galactic
nuclei in the MUSYC Extended Chandra Deep Field-South.
Cardamone C.N., Urry C.M., Damen M., Van Dokkum P., Treister E., Labbe I.,
Virani S.N., Lira P., Gawiser E.
<Astrophys. J., 680, 130-142 (2008)>
=2008ApJ...680..130C 2008ApJ...680..130C (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Surveys ; Cross identifications ;
Photometry, infrared ; X-ray sources
Keywords: infrared: galaxies - quasars: general - X-rays: galaxies
Abstract:
We present the mid-infrared colors of X-ray-detected AGNs and explore
mid-infrared selection criteria. Using a statistical matching
technique, the likelihood ratio, over 900 IRAC counterparts were
identified with a new MUSYC X-ray source catalog that includes ∼1000
published X-ray sources in the Chandra Deep Field-South and Extended
Chandra Deep Field-South. Most X-ray-selected AGNs have IRAC spectral
shapes consistent with power-law slopes, fν∝να,
and display a wide range of colors, -2≤alpha≤2 Although X-ray
sources typically fit to redder (more negative α) power laws
than non-X-ray-detected galaxies, more than 50% do have flat or blue
(galaxy-like) spectral shapes in the observed 3-8um band. Only a
quarter of the X-ray-selected AGNs detected at 24um are well fit by
featureless red power laws in the observed 3.6-24um, likely the subset
of our sample whose infrared spectra are dominated by emission from
the central AGN region. Most IRAC color selection criteria fail to
identify the majority of X-ray-selected AGNs, finding only the more
luminous AGNs, the majority of which have broad emission lines. In
deep surveys, these color selection criteria select 10%-20% of the
entire galaxy population and miss many moderate-luminosity AGNs.
Description:
The Multiwavelength Survey by Yale-Chile (MUSYC; Gawiser et al. 2006,
J/ApJS/162/1) is a square-degree survey of four fields to limiting
depths of RAB& and KAB" with extensive follow-up spectroscopy.
For this study, we use the two X-ray surveys that have overlapping
coverage one MUSYC field: the very deep central Chandra Deep
Field-South (CDF-S; G02, J/ApJS/139/369; A03, J/AJ/126/539) and the
deep ECDF-S (L05, J/ApJS/161/21; V06, J/AJ/131/2373). Recently, the
existing MUSYC data in the ECDF-S were augmented with very deep IRAC
Spitzer data in the SIMPLE survey (M. Damen et al. 2009, in
preparation) and by GOODS and the Spitzer Wide-area InfraRed
Extragalactic survey (SWIRE) at 24um.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 145 1017 X-ray and infrared properties of MUSYC
ECDF-S X-ray sources
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See also:
II/253 : Chandra Deep Field South: multi-colour data (Wolf+, 2008)
III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005)
J/ApJS/183/295 : A K-selected catalog of the ECDFS from MUSYC (Taylor+, 2009)
J/A+A/478/83 : GOODS-South Field VLT/FORS2 redshifts. III. (Vanzella+, 2008)
J/AJ/134/1103 : MUSYC deep near-infrared imaging (Quadri+, 2007)
J/ApJS/162/1 : MUSYC: optical source catalog (Gawiser+, 2006)
J/AJ/131/2373 : Extended Chandra Deep Field-South survey (Virani+, 2006)
J/ApJS/161/21 : Extended Chandra Deep Field-South survey (Lehmer+, 2005)
J/ApJS/155/271 : Chandra Deep Field-South: Optical spectroscopy (Szokoly+,
2004)
J/AJ/126/539 : The Chandra Deep Fields North and South (Alexander+, 2003)
J/ApJS/139/369 : Chandra Deep Field South. 1 Ms catalog (Giacconi+, 2002)
J/MNRAS/328/150 : KX redshift survey (Croom+, 2001)
http://www.astro.yale.edu/MUSYC : MUSYC Public Data Release webpage
http://data.spitzer.caltech.edu/popular/simple : Online data from SIMPLE
(Spitzer's IRAC and MUSYC Public Legacy of the E-CDFS) survey
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Running MUSYC XR Source catalog number (1)
6- 12 A7 --- CatID Original catalog number (AYY:NNN) (2)
14- 22 F9.6 deg RAXdeg X-ray Right Ascension in decimal degrees (J2000)
24- 33 F10.6 deg DEXdeg X-ray Declination in decimal degrees (J2000)
35- 39 F5.2 --- HR X-ray Hardness Ratio (3)
41- 49 F9.2 uJy F3.6 ?=99.00 IRAC Channel 1 (3.6um) flux density
51- 56 F6.2 uJy e_F3.6 ?=33.00 The 1σ error for F3.6um
58- 66 F9.2 uJy F4.5 ?=99.00 IRAC Channel 2 (4.5um) flux density
68- 73 F6.2 uJy e_F4.5 ?=33.00 The 1σ error for F4.5um
75- 83 F9.2 uJy F5.8 ?=99.00 IRAC Channel 3 (5.8um) flux density
85- 90 F6.2 uJy e_F5.8 ?=33.00 The 1σ error for F5.8um
92-100 F9.2 uJy F8.0 ?=99.00 IRAC Channel 4 (8.0um) flux density
102-107 F6.2 uJy e_F8.0 ?=33.00 The 1σ error for F8.0um
109 A1 --- r_F24 Source Catalog for MIPS 24 micron flux (4)
111-117 F7.2 uJy F24 ?=99.00 Spitzer/MIPS 24 micron flux
119-125 F7.2 uJy e_F24 ?=33.00 The 1σ error for F24um
127-132 F6.2 [10-7W] logLX ?=1.00 Log of X-ray luminosity in units of
erg/s (5)
134-135 I2 --- r_logLX ?=1 Source of redshift (6)
137-145 A9 --- notes Emission lines comment (7)
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Note (1): Sources are <[CUD2008] NNNN> in Simbad.
Note (2): Original detection catalog for X-ray source and X-ray source ID:
G02 =Giacconi et al. 2002, Cat. J/ApJS/139/369 (<[GZW2002] XID NNN>
or in Simbad)
A03 =Alexander et al. 2003, Cat. J/AJ/126/539 (<[ABB2003] CDFS NNN> in
Simbad)
L05 =Lehmer et al. 2005, Cat. J/ApJS/161/21 (<[LBA2005] NNN>
or in Simbad)
V06 =Virani et al.2006., Cat. J/AJ/131/2373 (<[VTU2006] NNN>
or in Simbad)
Note (3): Hardness ratio, defined by (H-S)/(H+S), where H and S are the
X-ray counts in the hard (2-8keV) and soft (0.5-2keV) bands,
respectively. For sources detected only in the hard band (soft band),
the hardness ratio is set equal to 1 (-1). For sources detected only
in the full band (0.5-8keV), the hardness ratio is set equal to 10.
G02 (Giacconi et al. 2002, Cat. J/ApJS/139/369) defined the hard band
as 2-10keV. Therefore, we adjusted the published hard band counts from
G02 to equal those that would have been detected at 2-8keV, using
PIMMS with the average X-ray spectrum measured by G02.
Note (4): Source of 24 micron flux as follows:
S =SWIRE (Lonsdale et al., 2003PASP..115..897L 2003PASP..115..897L),
G =GOODS (Dickinson et al., 2003mglh.conf..324D).
Note (5): Observed luminosity in the 0.5-8keV band, using references
given in final column.
Note (6): Source of redshift used to calculate the luminosity as follows:
0 =VLT/FORS2 Spectroscopy Version 1.0
1 =VIMOS VLT Deep Survey (VVDS) Version 1.0 (Cat. III/250)
2 =spectroscopic redshifts from Szokoly et al. (2004, Cat. J/ApJS/155/271)
3 =spectroscopic redshifts from Croom et al. (2001, Cat. J/MNRAS/328/150)
4 =spectroscopic redshifts from MUSYC Treister et al. (2009ApJ...693.1713T 2009ApJ...693.1713T)
5 =photometric redshifts from COMBO-17 Wolf et al. (2004, Cat. II/253)
Note (7): Classification as follows:
BLAGN =spectra showing broad emission lines (BL);
non-BLAGN =spectra without broad lines;
star =stellar source;
ELG =emission line galaxy;
ALG =absorption line galaxy.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 13-Oct-2010