Broad Line Region structure
Recent studies on X-ray absorption variability on time scales of hours/days
demonstrate that the X-ray "torus" is made of clouds with the same density and
distance from the center as the BLR emission line clouds, thus suggesting a
close link between the BLR and the X-ray circumnuclear absorber. Until now,
this approach has been applied to a small number of cases. However, more long
X-ray observations of bright sources with XMM-Newton and Suzaku, suitable for
absorption variability analysis, are present in public archives and hence this
X-ray absorption analysis can be applied to other sources. The idea is
that the results of these observational studies will be fundamental for a
better physical description of the absorbers and, therefore,for a better
knowledge of the actual structure of the BLR. The analysis is in progress.