AGN structure from X-ray absorption variability.

I present new results from time-resolved X-ray spectroscopy of bright obscured AGNs, showing column density variability on short time-scale (from hours to a few weeks). A simple analysis of these variations shows that the circumnuclear absorber must be made of clouds with densities of the order of 1010–1011 cm-3, located at distances of the order of 104 gravitational radii from the center. This strongly suggests an identification between the X-ray absorber and the BLR clouds. [ABSTRACT FROM AUTHOR]