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One of the most peculiar characteristics of Active Galactic Nuclei (AGN) istheir variability over all wavelengths. This property has been used in the pastto select AGN samples and is foreseen to be one of the detection techniquesapplied in future multi-epoch surveys, complementing photometric andspectroscopic methods.  In this paper, we aim to construct and characterise an AGN sample using amulti-epoch dataset in the r band from the SUDARE-VOICE survey.  Our work makes use of the VST monitoring program of an area surrounding theChandra Deep Field South to select variable sources. We use data spanning a sixmonth period over an area of 2 square degrees, to identify AGN based on theirphotometric variability.  The selected sample includes 175 AGN candidates with magnitude r < 23 mag. Wedistinguish different classes of variable sources through their lightcurves, aswell as X-ray, spectroscopic, SED, optical and IR information overlapping withour survey.  We find that 12% of the sample (21/175) is represented by SN. Of theremaining sources, 4% (6/154) are stars, while 66% (102/154) are likely AGNsbased on the available diagnostics. We estimate an upper limit to thecontamination of the variability selected AGN sample of about 34%, but we pointout that restricting the analysis to the sources with availablemulti-wavelength ancillary information, the purity of our sample is close to80% (102 AGN out of 128 non-SN sources with multi-wavelength diagnostics). Ourwork thus confirms the efficiency of the variability selection method inagreement with our previous work on the COSMOS field; in addition we show thatthe variability approach is roughly consistent with the infrared selection.

SUDARE-VOICE variability-selection of Active Galaxies in the Chandra Deep Field South and the SERVS/SWIRE region