J/MNRAS/495/1853 SED-selected AGN in the VIPERS field (Pouliasis+, 2020)
An obscured AGN population hidden in the VIPERS galaxies:
identification through spectral energy distribution decomposition
Pouliasis E., Mountrichas G., Georgantopoulos I., Ruiz A., Yang M.,
Bonanos A.Z.
<Mon. Not. R. Astron. Soc. 495, 1853 (2020)>
=2020MNRAS.495.1853P 2020MNRAS.495.1853P (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, IR ; X-ray sources ; Redshifts
Keywords: methods: data analysis - methods: observational -
methods: statistical - galaxies: active - infrared: galaxies -
X-rays: galaxies
Abstract:
The detection of X-ray emission constitutes a reliable and efficient
tool for the selection of active galactic nuclei (AGNs), although it
may be biased against the most heavily absorbed AGNs. Simple
mid-infrared (IR) broad-band selection criteria identify a large
number of luminous and absorbed AGNs, yet again host contamination
could lead to non-uniform and incomplete samples. Spectral energy
distribution (SED) decomposition is able to decouple the emission from
the AGN versus that from star-forming regions, revealing weaker AGN
components. We aim to identify the obscured AGN population in the
VIMOS Public Extragalactic Redshift Survey in the
Canada-France-Hawaii Telescope Legacy Survey W1 field through SED
modelling. We construct SEDs for 6860 sources and identify 160 AGNs at
a high confidence level using a Bayesian approach. Using optical
spectroscopy, we confirm the nature of ∼85 per cent of the AGNs. Our
AGN sample is highly complete (∼92 per cent) compared to mid-IR
colour-selected AGNs, including a significant number of
galaxy-dominated systems with lower luminosities. In addition to the
lack of X-ray emission (80 per cent), the SED fitting results suggest
that the majority of the sources are obscured. We use a number of
diagnostic criteria in the optical, IR, and X-ray regimes to verify
these results. Interestingly, only 35 per cent of the most luminous
mid-IR-selected AGNs have X-ray counterparts suggesting strong
absorption. Our work emphasizes the importance of using SED
decomposition techniques to select a population of type II AGNs, which
may remain undetected by either X-ray or IR colour surveys.
Description:
Catalogue of the 160 AGNs that were selected through spectral energy
distribution (SED) decomposition in the VIPERS field. The SEDs were
constructed using data from the optical (CFHTLS, Hudelot et al. 2012,
Cat. II/317), near-infrared (VISTA Hemisphere Survey, McMahon et al.
2013Msngr.154...35M 2013Msngr.154...35M, Cat. II/352) and mid-infrared bands (AllWISE,
Cutri & et al., 2013, Cat. II/328). We provide the positions, the
spectroscopic redshifts (VIPERS, Scodeggio et al.,
2018A&A...609A..84S 2018A&A...609A..84S), the infrared and X-ray (also upper limits)
luminosity and the AGN type of these 160 sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 65 160 Catalogue of the 160 SED-selected AGNs
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See also:
II/317 : The CFHTLS Survey (T0007 release) (Hudelot+ 2012)
II/352 : The VISTA Hemisphere Survey (VHS) catalog (McMahon+, 2013)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/A+A/562/A23 : VIMOS Public Extragalactic Survey (VIPERS) DR1 (Garilli+ 2014)
J/ApJ/642/673 : IR-selected obscured AGN candidates (Polletta+, 2006)
J/ApJ/702/441 : Obscured active galaxies (Greene+, 2009)
J/ApJ/740/37 : Obscured AGN at z∼0.5-1 in the CDFS (Luo+, 2011)
J/A+A/556/A114 : Obscured AGNs in XMM deep survey in CDF-S
(Castello-Mor+, 2013)
J/ApJ/814/11 : Obscured AGNs from XMM-Newton and AKARI (Terashima+, 2015)
J/A+A/618/A66 : Redshifts of obscured AGN (Simmonds+, 2018)
J/A+A/626/A9 : Obscured AGN at 1.5<z<3.0 (Mignoli+, 2019)
J/A+A/636/A37 : High-z AGN obscured by host galaxy ISM (D'Amato+, 2020)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- VIPERS VIPERS identifier
11- 18 F8.5 deg RAdeg Right ascension (J2000)
20- 27 F8.5 deg DEdeg Declination (J2000)
29- 33 F5.3 --- z Redshift
35- 39 F5.2 10-7W LIR Luminosity in the infrared
41 A1 --- l_LX Upper limit flag on LX
42- 46 F5.2 10-7W LX Luminosity in the X-ray (2-10keV) band
48 I1 --- mid-IR [0/1] 1 (0) if AGN is (is not) selected
via through mid-IR colours
50 I1 --- Broad-lines [0/1] 1 (0) for existence (absence) of
broad lines
52 I1 --- [NeV]-em [0/1] 1 (0) if AGN is (is not) selected
via [NeV] emission
54 I1 --- MEx [0/1] 1 (0) if AGN is (is not) selected
via MEx diagram
56 I1 --- TBT [0/1] 1 (0) if AGN is (is not) selected
via TBT diagram
58- 60 F3.1 --- SED-type AGN type derived from the SED fitting
results (ψ value)
62- 65 F4.2 mag r-W2 r-W2 colour index
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Acknowledgements:
Ektoras Pouliasis, ektoraspou(at)gmail.com
(End) Patricia Vannier [CDS] 29-May-2020