J/ApJ/728/38 AEGIS: demographics of X-ray and optical AGN (Yan+, 2011)
AEGIS: demographics of X-ray and optically selected active galactic nuclei.
Yan R., Ho L.C., Newman J.A., Coil A.L., Willmer C.N.A., Laird E.S.,
Georgakakis A., Aird J., Barmby P., Bundy K., Cooper M.C., Davis M.,
Faber S.M., Fang T., Griffith R.L., Koekemoer A.M., Koo D.C., Nandra K.,
Park S.Q., Sarajedini V.L., Weiner B.J., Willner S.P.
<Astrophys. J., 728, 38 (2011)>
=2011ApJ...728...38Y 2011ApJ...728...38Y
ADC_Keywords: Active gal. nuclei ; Spectroscopy ; Surveys ; X-ray sources ;
Galaxies, optical ; Redshifts ; Cross identifications
Keywords: galaxies: active - galaxies: fundamental parameters -
galaxies: nuclei - galaxies: Seyfert - galaxies: statistics
Abstract:
We develop a new diagnostic method to classify galaxies into active
galactic nucleus (AGN) hosts, star-forming galaxies, and
absorption-dominated galaxies by combining the [OIII]/Hβ ratio
with rest-frame U-B color. This can be used to robustly select AGNs in
galaxy samples at intermediate redshifts (z<1). We compare the result
of this optical AGN selection with X-ray selection using a sample of
3150 galaxies with 0.3<z<0.8 and IAB<22, selected from the DEEP2
Galaxy Redshift Survey and the All-wavelength Extended Groth Strip
International Survey. Among the 146 X-ray sources in this sample, 58%
are classified optically as emission-line AGNs, the rest as
star-forming galaxies or absorption-dominated galaxies. The latter are
also known as "X-ray bright, optically normal galaxies" (XBONGs).
Description:
The AEGIS-X survey (Laird et al. 2009, Cat. J/ApJS/180/102) has
obtained 200ks exposures over the entire Extended Groth Strip (EGS;
Davis et al. 2007ApJ...660L...1D 2007ApJ...660L...1D; see Section 2.2.1) using Chandra
ACIS-I. It covers an area of 0.67deg2 and reaches a limiting flux of
5.3x10-17erg/cm2/s in the 0.5-2keV band and 3.8x10-16erg/cm2/s
in the 2-10keV band at the deepest point.
DEEP2 is a galaxy redshift survey using the DEIMOS spectrograph on the
Keck-II telescope (Davis et al. 2003SPIE.4834..161D 2003SPIE.4834..161D; J. A. Newman et
al. 2012arXiv1203.3192N 2012arXiv1203.3192N). It covered four widely separated fields
totaling 3deg2 on the sky down to a limiting magnitude of RAB=24.1.
In the EGS, the survey obtained ∼17775 spectra with 12651 yielding
reliable redshifts. DEEP2 spectra typically cover approximately
6500-9200Å with a resolution of R∼5000.
Out of the 895 optically identified X-ray sources, 375 were observed
as part of the DEEP2 survey, yielding 249 successful redshifts (66.4%)
including 5 stars and 244 galaxies.
We obtained additional spectra using the Hectospec fiber spectrograph
on MMT for as many X-ray sources with optical counterparts as
possible. The observations and data reduction are described in detail
by Coil et al. (2009ApJ...701.1484C 2009ApJ...701.1484C). The spectra have a resolution of
6Å and cover a wavelength range of approximately 4500-9000Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 106 374 Optical properties of all X-ray sources and
optically classified AGNs in our sample
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2012)
J/A+A/526/A72 : Early-type galaxies in the EGS (Fernandez Lorenzo+, 2011)
J/ApJS/193/30 : UV-to-FIR analysis of sources in the EGS. II. (Barro+, 2011)
J/ApJ/717/1181 : Spitzer power-law galaxies in EGS (Park+, 2010)
J/ApJ/703/2160 : The OPTX project. III. (Trouille+, 2009)
J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009)
J/ApJS/180/102 : AEGIS-X: Chandra deep survey (Laird+, 2009)
J/ApJ/654/115 : DEEP2 Galaxy Redshift Survey: SDSS QSOs (Coil+, 2007)
J/A+A/466/31 : The HELLAS2XMM survey. VIII (Cocchia+, 2007)
J/MNRAS/356/568 : Deep Chandra survey of the Groth Strip (Nandra+, 2005)
J/ApJ/602/231 : Chandra X-ray sources in nearby galaxies (Colbert+, 2004)
J/ApJS/121/473 : A diagnostic diagram for Seyfert 2 Galaxies (Bassani+, 1999)
J/ApJS/112/315 : Spectroscopic parameters of Seyfert nuclei (Ho+ 1997)
J/ApJS/98/477 : Optical spectral atlas of Seyfert nuclei (Ho+ 1995)
J/ApJS/95/1 : Atlas of Quasar Energy Distributions (Elvis+ 1994)
J/ApJS/80/531 : An X-ray catalog and atlas of galaxies. (Fabbiano+, 1992)
http://aegis.ucolick.org/ : AEGIS home page
http://deep.berkeley.edu/ : DEEP2 redshift survey home page
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/374] Extended Groth Strip AGN number
5- 12 A8 --- [LNG2009] Laird et al. 2009 (Cat. J/ApJS/180/102)
identifier (egs_NNNN) (1)
14- 21 I8 --- DEEP2-GRS DEEP2 Galaxy Redshift Survey identifier (2)
23- 31 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
33- 40 F8.5 deg DEdeg Declination in decimal degrees (J2000)
42- 47 F6.4 --- z [0.3/0.9] Redshift
49- 53 F5.2 mag Imag [17.9/22] The I band (AB) magnitude
55- 59 F5.2 mag U-B ? Restframe (U-B) (AB) color index
61 A1 --- f_U-B [*] object in B-band drop out (3)
63 A1 --- l_logO3 Limit flag on logO3
64- 69 F6.2 [mW/m2] logO3 Log of [OIII] flux; erg/s/cm2
71- 74 F4.2 [mW/m2] e_logO3 ? Uncertainty in logO3
76 A1 --- l_logHb Limit flag on logHb
77- 82 F6.2 [mW/m2] logHb Log of Hβ flux; erg/s/cm2
84- 87 F4.2 [mW/m2] e_logHb ? Uncertainty in logHb
89 A1 --- l_O3/Hb Limit flag on O3/Hb
90- 94 F5.2 [-] O3/Hb ? Log ratio of [OIII] to Hβ fluxes
96 I1 --- s [1/2] Source of z, [OIII], & Hβ (4)
98-106 A9 --- Class Classification (5)
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Note (1): X-ray undetected sources have no ID.
Sources are <[LNG2009] egs-NNNN> in Simbad.
Note (2): see http://deep.berkeley.edu/DR1/photo.primer.html (Cat. VII/263)
Note (3):
* = DEEP2 Object 11027275 is a B-band drop out; its U-B color is not available.
Note (4): Source as follows:
1 = DEEP2;
2 = MMT/Hectospec follow-up.
Note (5): Classification as follows:
AGN-1 = Type 1 AGN;
AGN-2 = optically selected Type 2 AGN, including both X-ray detected
and undetected;
SF+AGN = X-ray loud, composite galaxies;
XBONG = X-ray Bright, Optically Normal Galaxies;
Gal = X-ray detected normal galaxies;
Ambiguous = X-ray sources with ambiguous optical classifications;
Blended = known cases of blended objects for which the optical spectrum
and the X-rays are from different objects.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-Sep-2012