Interpretation of Departure from the Broad Line Region Scaling in Active Galactic Nuclei

Most results of the reverberationmonitoring of active galaxies showed a universal scaling of the time delay of the Hbeta emission region with the monochromaticflux at 5100 A, with very small dipersion. Such a scaling favored the dust-based formation mechanism of the Broad Line Region (BLR). Recent reverberationmeasurements showed that actually a significant fraction of objects exhibits horter lags than the previously found scaling. Here we demonstrate that these shorter lags can be explained by the old concept of scaling of the BLR size with the ionization parameter. Assuming a universal valueof this parameter and universal valueof the cloud density reproduces the distribution of observational points in the time delay vs. monochromaticflux plane, provided that a range of black hole spins is allowed. However, a confirmation of the new measurements for low/moderate Eddington ratio sources is strongly needed before the dust-based origin of the BLR can be excluded.