LINE-PROFILE AND VARIABILITY DATA TO PROBE THE BROAD-LINE REGION GEOMETRY - OF DISKS AND NESTS

We propose a simplified, bidimensional method to test the gas distribution in the broad-line regions of AGNs. Assuming the geometry of the distribution, we derive the transfer function by inverting the observed line profile. The predicted transfer function can be compared with the one derived independently from variability data. As an example we have applied this method to NGC 5548 assuming two different geometries: a disk, and a "nest." The former can reproduce very easily the line profile, but the two estimates of the transfer function are largely discrepant. The latter gives a transfer function which agrees with the observed one, at the expenses of a poorer fit to the line shape.