Extending the variability selection of active galactic nuclei in the
  W-CDF-S and SERVS/SWIRE region
  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 $\lesssim 20\%$ and a completeness $\sim 38\%$ with
respect to mid-infrared selected samples.
