J/MNRAS/487/4285 Variable AGN candidates catalog (Pouliasis+, 2019)
Robust identification of active galactic nuclei through HST optical variability
in GOODS-S: comparison with the X-ray and mid-IR-selected samples.
Pouliasis E., Georgantopoulos I., Bonanos A.Z., Yang M., Sokolovsky K.V.,
Hatzidimitriou D., Mountrichas G., Gavras P., Charmandaris V.,
Bellas-velidis I., Spetsieri Z.T., Tsinganos K.
<Mon. Not. R. Astron. Soc., 487, 4285-4304 (2019)>
=2019MNRAS.487.4285P 2019MNRAS.487.4285P (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; X-ray sources ; Magnitudes ; Redshifts
Keywords: methods: observational - galaxies: active - galaxies: nuclei -
galaxies: photometry - X-rays: galaxies
Abstract:
Identifying active galactic nuclei (AGNs) through their X-ray emission
is efficient, but necessarily biased against X-ray-faint objects. We
aim to characterize this bias by comparing X-ray-selected AGNs to the
ones identified through optical variability and mid-infrared (mid-IR)
colours. We present a catalogue of AGNs selected through optical
variability using all publicly available z-band Hubble Space Telescope
images in the GOODS-South field. For all objects in the catalogue, we
compute X-ray upper limits or discuss detections in the deepest
available ∼7 Ms Chandra Deep Field South images and present the
Spitzer/Infrared Array Camera (IRAC) mid-IR colours. For the
variability study, we consider only sources observed over at least
five epochs and over a time baseline of up to 10yr. We adopt the
elevated median absolute deviation as a variability indicator robust
against individual outlier measurements and identify 113
variability-selected AGN candidates. Among these, 26 have an X-ray
counterpart and lie within the conventional AGN area in the FX/Fopt
diagram. The candidates with X-ray upper limits are on average
optically fainter, have higher redshifts compared to the
X-ray-detected ones and are consistent with low-luminosity AGNs. Out
of 41 variable optical sources with IR detections, 13 fulfill the IR
AGN colour selection criteria. Our work emphasizes the importance of
optical variability surveys for constructing complete samples of AGNs
including the ones that remain undetected even by the deepest X-ray
and IR surveys.
Description:
Based on observations made with the NASA/ESA Hubble Space Telescope,
and obtained from the Hubble Legacy Archive, which is a collaboration
between the Space Telescope Science Institute (STScI/NASA), the Space
Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian
Astronomy Data Centre (CADC/NRC/CSA).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 70 113 Catalogue of the variable AGN candidates
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See also:
J/A+A/488/73 : Variability-selected AGN in Chandra DFS (Trevese+, 2008)
J/A+A/497/81 : Variability-selected AGN in CDFS (Boutsia+, 2009)
J/ApJ/723/737 : GOODS variability selected AGNs catalog (Villforth+, 2010)
J/A+A/536/A84 : X-ray variability of AGN (Vagnetti+, 2011)
J/ApJ/731/97 : Variable AGNs in GOODS fields (Sarajedini+, 2011)
J/ApJ/748/124 : AGN X-ray variability in the 4Ms catalog (Young+, 2012)
J/A+A/579/A115 : SUDARE-VOICE variability-selection of AGN (Falocco+, 2015)
J/A+A/584/A106 : Catalogues of variable AGNs (Simm+, 2015)
J/AZh/93/605 : AGN long-term variability (Volvach+, 2016)
J/A+A/627/A33 : Optically variable AGN in COSMOS field (De Cicco+, 2019)
J/A+A/634/A50 : Optically variable AGN in the VST/CDF-S (Poulain+, 2020)
J/ApJS/232/8 : 16yrs of 7Ms CDF-S AGNs X-ray spectral analyses (Liu+, 2017)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identifier
7 A1 --- Grade Quality grade
9- 16 F8.5 deg RAdeg Right ascension (J2000)
18- 26 F9.5 deg DEdeg Declination (J2000)
28- 29 I2 --- Np Number of data points in the light curve
31- 34 F4.2 yr Tbas Time baseline
36- 39 F4.2 mag CI Concentration index
41- 45 F5.2 mag <F850LP> Median magnitude in the F850LP filter
47- 51 F5.2 --- MAD* Normalized significance
53- 56 F4.2 --- z Redshift
58 I1 --- Meth [1/3] Method used to compute z (1)
59 A1 --- --- [,]
60 A1 --- r_z Redshift reference (2)
62 A1 --- l_FX Upper limit flag on FX
63- 70 E8.3 mW/m2 FX Flux in the X-ray (0.5-8keV) band
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Note (1): Method used to compute z as follows:
1 = spectroscopy
2 = grism
3 = photometry)
Note (2): Paper where the redshift obtained as follows:
a = Luo et al. (2017ApJS..228....2L 2017ApJS..228....2L, Cat. J/ApJS/228/2),
b = Momcheva et al. (2016ApJS..225...27M 2016ApJS..225...27M, Cat. J/ApJS/225/27)
c = Cardamone et al. (2010ApJS..189..270C 2010ApJS..189..270C, Cat. J/ApJS/189/270)
d = Straatman et al. (2016ApJ...830...51S 2016ApJ...830...51S, Cat. J/ApJ/830/51)
e = Xue et al. (2016ApJS..224...15X 2016ApJS..224...15X, Cat. J/ApJS/224/15)
f = Taylor et al. (2009ApJS..183..295T 2009ApJS..183..295T, Cat. J/ApJS/183/295)
g = Wolf et al. (2008A&A...492..933W 2008A&A...492..933W)
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Acknowledgements:
Ektoras Pouliasis, ektoraspou(at)gmail.com
(End) Patricia Vannier [CDS] 26-Mar-2020