Osservatorio Astrofisico di Arcetri

Guidetta Torricelli

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.