J/A+A/634/A50 Optically variable AGN in the VST/CDF-S (Poulain+, 2020)
Extending the variability selection of active galactic nuclei in the W-CDF-S
and SERVS/SWIRE region.
Poulain M., Paolillo M., De Cicco D., Brandt W.N., Bauer F.E., Falocco S.,
Vagnetti F., Grado A., Ragosta F., Botticella M.T., Cappellaro E.,
Pignata G., Vaccari M., Schipani P., Covone G., Longo G., Napolitano N.R.
<Astron. Astrophys. 634, A50 (2020)>
=2020A&A...634A..50P 2020A&A...634A..50P (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Magnitudes ; Redshifts
Keywords: galaxies: active - infrared: galaxies - surveys
Abstract:
Variability has proven to be a powerful tool to detect active galactic
nuclei (AGN) in multi-epoch surveys. The new-generation facilities
expected to become operational in the next few years will mark a new
era in time-domain astronomy and their wide-field multi-epoch
campaigns will favor extensive variability studies.
We present our analysis of AGN variability in the second half of the
VST survey of the Wide Chandra Deep Field South (W-CDF-S), performed
in the r band and covering a 2 sq. deg. area. The analysis complements
a previous work, in which the first half of the area was investigated.
We provide a reliable catalog of variable AGN candidates, which will
be critical targets in future variability studies.
We selected a sample of optically variable sources , and made use of
infrared data from the Spitzer mission to validate their nature by
means of color-based diagnostics.
We obtain a sample of 782 AGN candidates among which 12 are classified
as supernovae, 54 as stars, and 232 as AGN. We estimate a
contamination ≲ 20% and a completeness ∼38% with respect to
mid-infrared selected samples.
Description:
This work is based on data in the r band from the SUDARE-VOICE survey
performed with the VST telescope (Botticella et al.,
2013Msngr.151...29B 2013Msngr.151...29B; Cappellaro et al., 2015A&A...584A..62C 2015A&A...584A..62C, Cat.
J/A+A/584/A62). The data are centred on the Wide Chandra Deep Field
South (W-CDF-S), covering an area of 2 sq. deg., in the u, g, r, i
bands. The first half of this area has been studied in Falocco et al.
(2015A&A...579A.115F 2015A&A...579A.115F, Cat. J/A+A/579/A115) and we focus here on the
second half.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 77 782 List of the 782 optically variable sources in
the sample
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See also:
J/A+A/579/A115 : SUDARE-VOICE variability-selection of AGN (Falocco+, 2015)
J/A+A/584/A62 : SUDARE VST-OmegaCAM search supernova rates (Cappellaro+, 2015)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Field Field (CDF-S3 or CDF-S4)
10- 12 I3 --- ID [1/782] Sequential identification number
17- 23 F7.4 deg RAdeg Right ascension (J2000)
27- 34 F8.4 deg DEdeg Declination (J2000)
38- 42 F5.2 mag rmagavg Average VST r magnitude (AB)
46- 49 F4.2 mag ltcrms r.m.s. of the light curve
53- 54 I2 --- Percentile Percentile (1)
60- 63 F4.2 --- z ? Redshift (2)
67- 70 F4.2 --- S/G SExtractor stellarity index
74- 77 A4 --- Class Source classification (3)
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Note (1): the number indicates that the light curve r.m.s. of the source is
above the threshold of the corresponding percentile.
Note (2): when available, spectroscopic redshifts from Vaccari
(2015fers.confE..27V). see http://www.mattiavaccari.net/df/specz/ for more
information about SERVS-SWIRE spectroscopic redshifts
Note (3): The classification index is the sum of different numbers corresponding
to the following key:
-2 = confirmed supernova
-1 = star from NIR/optical diagnostic
0 = no available classification
1 = AGN from mid-IR diagnostic, Lacy region
2 = AGN from mid-IR diagnostic, Stern region
3 = AGN from mid-IR diagnostic, Donley region
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Acknowledgements:
Melina Poulain, melina.poulain45(at)gmail.com
(End) Patricia Vannier [CDS] 30-Dec-2019