Extending the variability selection of active galactic nuclei in the W-CDF-S and SERVS/SWIRE region

Abstract

Context. 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. <BR /> Aims: We present our analysis of AGN variability in the second half of the VST survey of the Wide Chandra Deep Field South, 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. <BR /> Methods: 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. <BR /> Results: 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. <P />Full Table 3 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/634/A50">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/634/A50</A>