Indiv. opt. variability of AGNs from MEXSAS2

Nevertheless, it is interesting to provide estimates of the individual variability properties of each AGN, in order to relate them with intrinsic physical quantities. A useful dataset is provided by the Catalina Surveys Data Release 2 (CSDR2), which encompasses almost a decade of photometric measurements of ~500 million objects repeatedly observed hundreds of times.We aim to investigate the individual optical variability properties of 795 AGNs originally included in the Multi-Epoch XMMSerendipitous AGN Sample 2 (MEXSAS2).

Our goals consist in: (i) searching for correlations between variability and AGN physical quantities; (ii) extending our knowledge of the variability features of MEXSAS2 from the X-ray to the optical.We use the structure function (SF) to analyse AGN flux variations. We model the SF as a power-law, SF(tau)=A(tau/tau_0)^gamma^, and we compute its variability parameters. We introduce the V-correction as a simple tool to correctly quantify the amount of variability in the rest frame of each source.We find a significant decrease of variability amplitude with increasing bolometric, optical and X-ray luminosity.