SIMBAD references

Most results of the reverberation monitoring of active galaxies showed a universal scaling of the time delay of the Hβ emission region with the monochromatic flux at 5100 Å, with very small dispersion. Such a scaling favored the dust-based formation mechanism of the broad-line region (BLR). Recent reverberation measurements showed that actually a significant fraction of objects exhibit shorter 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 value of this parameter and a universal value of the cloud density reproduces the distribution of observational points in the time delay-monochromatic flux 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.