On variability in obscured and unobscured AGNs

Quasars belong to the most energetic phenomena in the universe. Physical
processes at the origin of them can be explained in the framework of the
AGN unified scenario. The unified scenario predicts two classes of
quasars, obscured and unobscured ones, depending on the orientation of
the dusty torus which surrounds the central supermassive black hole.
Variability is ubiquitous in AGN, and may be generated by several
phenomena that would produce different footprints. Determining the
nature and origin of the variability is a key subject to understand the
differences between the different types of AGNs.