J/MNRAS/468/196 The invisible AGN catalogue (Truebenbach+, 2017)
The invisible AGN catalogue: a mid-infrared-radio selection method for
optically faint active galactic nuclei.
Truebenbach A.E., Darling J.
<Mon. Not. R. Astron. Soc., 468, 196-206 (2017)>
=2017MNRAS.468..196T 2017MNRAS.468..196T (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Radio sources ; Infrared sources ;
Photometry, millimetric/submm
Keywords: methods: data analysis - catalogues - galaxies: active -
galaxies: evolution - infrared: galaxies - radio continuum: galaxies
Abstract:
A large fraction of active galactic nuclei (AGN) are 'invisible' in
extant optical surveys due to either distance or dust-obscuration. The
existence of this large population of dust-obscured, infrared
(IR)-bright AGN is predicted by models of galaxy-supermassive black
hole coevolution and is required to explain the observed X-ray and IR
backgrounds. Recently, IR colour cuts with Wide-field Infrared Survey
Explorer have identified a portion of this missing population.
However, as the host galaxy brightness relative to that of the AGN
increases, it becomes increasingly difficult to differentiate between
IR emission originating from the AGN and from its host galaxy. As a
solution, we have developed a new method to select obscured AGN using
their 20-cm continuum emission to identify the objects as AGN. We
created the resulting invisible AGN catalogue by selecting objects
that are detected in AllWISE (mid-IR) and FIRST (20 cm), but are not
detected in SDSS (optical) or 2MASS (near-IR), producing a final
catalogue of 46 258 objects. 30 per cent of the objects are selected
by existing selection methods, while the remaining 70 per cent
represent a potential previously unidentified population of candidate
AGN that are missed by mid-IR colour cuts. Additionally, by relying on
a radio continuum detection, this technique is efficient at detecting
radio-loud AGN at z≥0.29, regardless of their level of dust
obscuration or their host galaxy's relative brightness.
Description:
We have created a new method for selecting obscured AGN that is
unbiased towards heavily obscured AGN and AGN with high levels of host
galaxy contamination. We selected objects that are detected in AllWISE
and FIRST, but are not detected in SDSS or 2MASS. By excluding all
optically detected sources and requiring a detection in AllWISE, we
have biased our catalogue towards the most heavily obscured AGN, which
are also most frequently missed by other selection methods. By
including a FIRST requirement, we have introduced an easier, cleaner
way to identify AGN that does not rely on WISE colour cuts.
Our method selected 46258 obscured AGN candidates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 259 46258 Invisible AGN Catalogue
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See also:
II/328 : AllWISE Data Release (Cutri+, 2013)
VIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+, 2015)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- FIRST ID as it appears in FIRST Catalogue
21- 30 F10.6 deg RAdeg Right ascension from FIRST Catalogue (J2000)
33- 37 F5.2 arcsec e_RAdeg Uncertainty (90% confidence) of FIRST
right ascension (1)
42- 51 F10.6 deg DEdeg Declination from FIRST Catalogue (J2000)
54- 58 F5.2 arcsec e_DEdeg Uncertainty (90% confidence) of
FIRST declination (1)
61- 67 F7.2 mJy F1.4GHz 1.4GHz integrated flux density from FIRST
71- 75 F5.3 mJy e_F1.4GHz Local noise estimate at the source position
79- 97 A19 --- AllWISE AllWISE ID as it appears in AllWISE Catalogue
98 A1 --- Note [*] Note (2)
102-112 F11.7 deg RAAdeg Right ascension from AllWISE Catalogue
116-121 F6.4 arcsec e_RAAdeg 1-sigma uncertainty of WISE
right ascension (3)
126-136 F11.7 deg DEAdeg Declination from AllWISE Catalogue
139-145 F7.4 arcsec e_DEAdeg 1-sigma uncertainty of WISE declination (3)
148 A1 --- l_[3.4] Upper limit flag on [3.4]
149-154 F6.3 mag [3.4] 3.4 micron magnitude from AllWISE Catalogue
157-161 F5.3 mag e_[3.4] ? 1-sigma uncertainty on 3.4 micron magnitude
from the AllWISE Catalogue
166-169 F4.1 --- SNR3.4 ? 3.4 micron magnitude measurement
signal-to-noise ratio.
172 A1 --- l_[4.6] Upper limit flag on [4.6]
173-178 F6.3 mag [4.6] 4.6 micron magnitude from AllWISE Catalogue
181-185 F5.3 mag e_[4.6] ? 1-sigma uncertainty on 4.6 micron magnitude
from the AllWISE Catalogue
190-193 F4.1 --- SNR4.6 4.6 micron magnitude measurement
signal-to-noise ratio
197 A1 --- l_[12] Upper limit flag on [12]
198-203 F6.3 mag [12] ? 12 micron magnitude from AllWISE Catalogue
206-210 F5.3 mag e_[12] ? 1-sigma uncertainty on 12 micron magnitude
from the AllWISE Catalogue
214-218 F5.1 --- SNR12 ? 12 micron magnitude measurement
signal-to-noise ratio.
222 A1 --- l_[22] Upper limit flag on [22]
223-228 F6.3 mag [22] ? 22 micron magnitude from AllWISE Catalogue
231-235 F5.3 mag e_[22] ? 1-sigma uncertainty on 22 micron magnitude
from the AllWISE Catalogue
240-244 F5.1 --- SNR22 ? 22 micron magnitude measurement
signal-to-noise ratio.
249-252 F4.2 arcsec theta Angular separation between the FIRST source
and the AllWISE source
256-259 F4.2 arcsec e_theta 1-sigma uncertainty in the angular separation
calculated based on FIRST and WISE position
uncertainties
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Note (1): Calculated from the FIRST major axis, minor axis, and position angle
of the source, along with the sky RMS.
Note (2): * = Extended objects in AllWISE are marked with an asterisk.
Reported magnitudes may under represent the source flux density.
Note (3): Calculated from the WISE position angle and major and minor axes
uncertainties.
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History:
From electronic version of the journal,
Alexandra Truebenbach, alexandra.truebenbach(at)colorado.edu
(End) Patricia Vannier [CDS] 21-Mar-2020