Studying the X-ray/UV Variability of Active Galactic Nuclei with data from Swift and XMM archives

Many efforts have been made in understanding the underlying origin of variability in Active Galactic Nuclei (AGN), but at present they could give still no conclusive answers. Since a deeper knowledge of variability will enable to understand better the accretion process onto supermassive black holes, here we present preliminary results of the first ensemble structure function analysis of the X-ray variability of samples of quasars with data from Swift and XMM-Newton archives. Moreover, it is known that UV and X-ray luminosities of quasars are correlated and recent studies quantified this relation across 5 orders of magnitude. In this context, we present here some preliminary results on the X-ray/UV ratio from simultaneous observations in UV and X-ray bands of a sample of quasars with data from XMM-Newton archive.