J/ApJ/790/54 AGN models according to a UV to Mid-IR study (Chung+, 2014)
A UV to Mid-IR study of AGN selection.
Chung S.M., Kochanek C.S., Assef R., Brown M.J.I., Stern D., Jannuzi B.T.,
Gonzalez A.H., Hickox R.C., Moustakas J.
<Astrophys. J., 790, 54 (2014)>
=2014ApJ...790...54C 2014ApJ...790...54C (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Redshifts ; Models
Keywords: galaxies: active - galaxies: distances and redshifts -
quasars: general
Abstract:
We classify the spectral energy distributions (SEDs) of 431,038
sources in the 9 deg2 Bootes field of the NOAO Deep Wide-Field
Survey (NDWFS). There are up to 17 bands of data available per source,
including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and
mid-infrared (IRAC and MIPS) data, as well as spectroscopic redshifts
for ∼20,000 objects, primarily from the AGN and Galaxy Evolution
Survey. We fit galaxy, active galactic nucleus (AGN), stellar, and
brown dwarf templates to the observed SEDs, which yield spectral
classes for the Galactic sources and photometric redshifts and
galaxy/AGN luminosities for the extragalactic sources. The photometric
redshift precision of the galaxy and AGN samples are σ/(1 + z) =
0.040 and σ/(1 + z) = 0.169, respectively, with the worst 5%
outliers excluded. On the basis of the Χ_ν2 of the SED fit
for each SED model, we are able to distinguish between Galactic and
extragalactic sources for sources brighter than I = 23.5 mag. We
compare the SED fits for a galaxy-only model and a galaxy-AGN model.
Using known X-ray and spectroscopic AGN samples, we confirm that SED
fitting can be successfully used as a method to identify large
populations of AGNs, including spatially resolved AGNs with
significant contributions from the host galaxy and objects with the
emission line ratios of "composite" spectra. We also use our results
to compare with the X-ray, mid-IR, optical color, and emission line
ratio selection techniques. For an F-ratio threshold of F > 10, we
find 16,266 AGN candidates brighter than I = 23.5 mag and a surface
density of ∼1900 AGN deg-2.
Description:
The data used in this work consist of the extensive multiwavelength
imaging of the 9 deg2 NDWFS Bootes field and optical spectroscopy
from AGES (Kochanek et al. 2012, J/ApJS/200/8) and R. C. Hickox et al.
(2014, private communication). Data from NDWFS (BW, R, I, K) and
NEWFIRM (J, H, Ks) are based on the Vega magnitude system, and data
from GALEX, US, Y, and z bands are based on the AB system. All
magnitudes reported throughout this paper are kept in their native
zeropoint systems and refer to 6'' diameter aperture magnitudes unless
otherwise stated. Objects were detected using SExtractor 2.3.3 (Bertin
& Arnouts 1996A&AS..117..393B 1996A&AS..117..393B) run on the I-band images from the NDWFS
third data release. To obtain consistent aperture photometry across
the full Bootes field, the BW, R, I, Y, H, and KS images were smoothed
to a common point spread function (PSF) of 1.35'' FWHM, while the US,
z, and J images were smoothed to a common PSF of 1.60'' FWHM. We
measured the aperture photometry for each object using our own code.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 142 431038 Model results
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See also:
J/ApJ/664/761 : BVRI photometry of AGNs in clusters (Martini+, 2007)
J/ApJS/187/64 : The simultaneous optical-to-X-ray SED of AGNs (Grupe+, 2010)
J/A+A/529/A135 : AGN Opt/IR properties in Lockman Hole (Rovilos+, 2011)
J/AJ/144/11 : IR imaging, nuclear SEDs, Spitzer spectra of 22 AGNs
(Mason+, 2012)
J/ApJS/200/8 : AGES: the AGN and Galaxy Evolution Survey (Kochanek+, 2012)
J/MNRAS/437/968 : AGN automatic photometric classification (Cavuoti+, 2014)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Aperture Right Ascension (J2000)
11- 18 F8.5 deg DEdeg Aperture Declination (J2000)
20- 25 F6.2 mag Imag I band 6'' diameter aperture magnitude
27- 30 F4.2 --- S SExtractor stellarity index
(1 = point source)
32- 37 F6.2 --- zsp ?=-99.99 AGES spectroscopic redshift (1)
39- 42 A4 --- N Number of bands with detections/limits
used in fits
44- 47 F4.2 --- z(G) Galaxy-only model photometric redshift
49- 54 F6.2 --- chi2(G) Galaxy-only model reduced Χ2
56- 61 F6.3 [10+10Lsun] L(Ell) Log elliptical galaxy component
luminosity (2)
63- 68 F6.3 [10+10Lsun] L(Sbc) Log Sbc galaxy component luminosity (2)
70- 75 F6.3 [10+10Lsun] L(Irr) Log irregular galaxy component
luminosity (2)
77- 80 F4.2 --- z(G+A) Galaxy + AGN model photometric redshift
82- 87 F6.2 --- chi2(G+A) Galaxy + AGN model reduced Χ2
89- 94 F6.3 [10+10Lsun] L(AGN+) Log Galaxy+AGN model AGN component
luminosity (2)
96-101 F6.3 [10+10Lsun] L(Ell+) Log galaxy+AGN model elliptical galaxy
component luminosity (2)
103-108 F6.3 [10+10Lsun] L(Sbc+) Log galaxy+AGN model Sbc galaxy
component luminosity (2)
110-116 F7.3 [10+10Lsun] L(Irr+) Log galaxy+AGN model irregular galaxy
component luminosity (2)
118-124 F7.2 --- F F-ratio value compared to Galaxy-only
fit
126-129 F4.2 mag E(B-V) E(B-V) applied to AGN template
131-136 F6.2 --- chi2(S) Stellar model reduced Χ2
138-142 A5 --- SType Stellar type of best fit (3)
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Note (1): -99.99 = AGES redshift not available.
Note (2): Luminosities are calculated for the fit at the spectroscopic
redshift if known.
0.0 = the best fit included no contribution from that template.
Note (3): Where K/M means the best fit lay between the K and M stellar
templates and 2000K means the best fit was the 2000K brown dwarf
template. Uppercase letters refer to giant spectral templates and
lowercase letters refer to dwarf spectral templates.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 17-Mar-2017