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J/A+A/579/A115      SUDARE-VOICE variability-selection of AGN   (Falocco+, 2015)

SUDARE-VOICE variability-selection of active galaxies in the Chandra Deep Field-South and the SERVS/SWIRE region. Falocco S., Paolillo M., Covone G., De Cicco D., Longo G., Grado A., Limatola L., Vaccari M., Botticella M.T., Pignata G., Cappellaro E., Trevese D., Vagnetti F., Salvato M., Radovich M., Hsu L., Capaccioli M., Napolitano N., Brandt W.N., Baruffolo A., Cascone E., Schipani P. <Astron. Astrophys., 579, A115-115 (2015)> =2015A&A...579A.115F (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Photometry, SDSS ; Galaxies, IR Keywords: galaxies: active - surveys - infrared: galaxies Abstract: One of the most peculiar characteristics of active galactic nuclei (AGNs) is their variability over all wavelengths. This property has been used in the past to select AGN samples and is foreseen to be one of the detection techniques applied in future multi-epoch surveys, complementing photometric and spectroscopic methods. In this paper, we aim to construct and characterise an AGN sample using a multi-epoch dataset in the r band from the SUDARE-VOICE survey. Our work makes use of the VST monitoring programme of an area surrounding the Chandra Deep Field South to select variable sources. We use data spanning a six-month period over an area of 2 square degrees, to identify AGN based on their photometric variability. The selected sample includes 175 AGN candidates with magnitude r<23mag. We distinguish different classes of variable sources through their lightcurves, as well as X-ray, spectroscopic, SED, optical, and IR information overlapping with our survey. We find that 12% of the sample (21/175) is represented by supernovae (SN). Of the remaining sources, 4% (6/154) are stars, while 66% (102/154) are likely AGNs based on the available diagnostics. We estimate an upper limit to the contamination of the variability selected AGN sample ≃34%, but we point out that restricting the analysis to the sources with available multi-wavelength ancillary information, the purity of our sample is close to 80% (102 AGN out of 128 non-SN sources with multi-wavelength diagnostics). Our work thus confirms the efficiency of the variability selection method, in agreement with our previous work on the COSMOS field. In addition we show that the variability approach is roughly consistent with the infrared selection. 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; Cappellaro et al., in prep.; Vaccari et al., in prep.). The data are centred on the Chandra Deep Field South, covering an area of 2deg2, in the u, g, r, i bands. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 64 175 Results on the selected sample
See also: II/326 : Revised SWIRE photometric redshifts (Rowan-Robinson+, 2013) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 6 I6 --- ID Optical ID 8- 9 I2 h RAh Right ascension (J2000) 11- 12 I2 min RAm Right ascension (J2000) 14- 18 F5.2 s RAs Right ascension (J2000) 20 A1 --- DE- Declination sign (J2000) 21- 22 I2 deg DEd Declination (J2000) 24- 25 I2 arcmin DEm Declination (J2000) 27- 30 F4.1 arcsec DEs Declination (J2000) 32- 36 F5.2 mag <rmag> Average r band magnitude 38- 41 F4.2 --- Stell Stellarity index (from Sextractor, see text) 43- 46 F4.1 --- signi Significance of variability in rms units 48 I1 --- Qual [1/2] Quality flag defined in Sect. 4 (1) 50 I1 --- SN [0/1] SN (identified by their LC and confirmed in SUDARE-I, see Sect. 5.1) 52 I1 --- Star [0/1]?=- Stars identified with the diagnostic using r-i versus the 3.6um to r band flux ratio (see Sect. 5.3.1) 54 I1 --- AGNx [0/1]?=- X-ray detected/non-detected sources (2) 56 I1 --- AGNsp [0/1]?=- AGN validation by optical spectroscopy (Boutsia et al., 2009, Cat. J/A+A/497/81) 58 I1 --- AGNir [0/1]?=- Sources matching the Lacy et al. (2004ApJS..154..166L) IR criterion for AGN selection (see Sect. 5.3.2) 60 I1 --- AGNsed [0/1]?=- AGN validation by multi-wavelength SED fitting (3) 61 A1 --- n_AGNsed [*+] Note on AGNsed (4) 63- 64 I2 --- Class [-2/4]?=- Final source classification (5)
Note (1): Quality flag as follows: 1 = candidate is robust, with no evident photometric or aesthetic problems (60% of the 235 candidates) 2 = candidate is likely to be variable, and the photometry may be slightly affected by the presence of a nearby companion or by minor aesthetic defects (e.g. faint satellite tracks) (15%) 3 = candidate is very likely spurious, and its variability is uncertain (the remaining 25%) Note (2): Sources flagged with 1 (X-ray detected) and 0 (X-ray non-detected) (see Sect. 5.2) Note (3): from Rowan-Robinson et al. 2013MNRAS.428.1958R, Cat. II/326; Hsu et al., 2014ApJ...796...60H. Sources fitted by an AGN template are flagged with 1, otherwise with 0 Note (4): Flag as follows: * = sources in Rowan-Robinson et al. (2013MNRAS.428.1958R, Cat. II/326) + = sources in Hsu et al. (2014ApJ...796...60H) Note (5): This flag is obtained summing the individual AGN flags reported in Cols. (9)-(12). It is, thus, a positive number for AGN. The SN are indicated with flag -2 and the stars with flag 1.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 06-Oct-2015
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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