Characterization of the AGN variability in the optical and Near Infrared regimes

<p>Variability is one of the most defining characteristic of Active Galactic Nuclei (AGN), and it is observed in every waveband in which they have been studied. For this reason variability studies are fundamental to understand the extreme physical conditions of accretion disks near supermassive black holes. Several efforts have been done to analyze the variability in the optical range, however, in order to relate the variability and physical properties of AGN, we need well sampled light curves. On the other hand, very little is known about the variability in the infrared range. This waveband gives us information about the dust surrounding the accretion disk at low redshift, and about the accretion disk at high redshift.<br> In this talk, we will present the current status of our QUEST-La Silla AGN variability survey. This is an effort to obtain well sampled optical light curves of AGN in extragalactic fields with unique multiwavelength observations, using the QUEST camera on the ESO-Schmidt telescope.The survey uses a broadband filter, the Q-band, similar to the union of the g and the r filters. In particular, we will present the status of the analysis of the COSMOS, ELAIS-S1 and Stripe82 fields. Besides, we will present our statistical study of the near infrared (NIR) variability of AGN in the COSMOS field, using UltraVISTA data. This dataset give us a huge sample of light curves, making possible to have a global description of the nature of AGNs for different ranges of redshift, and for different levels of obscuration. By using both surveys, we expect to have a better understanding of the difference between type 1 and type 2 AGN.