2009ApJ...701L..91E

The disk-wind scenario for the broad-line region (BLR) and toroidal obscuration in active galactic nuclei (AGNs) predicts the disappearance of the BLR at low luminosities. In accordance with the model predictions, data from a nearly complete sample of nearby AGNs show that the BLR disappears at luminosities lower than 5x10³⁹(M/10⁷ M_☉)^2/3 erg/s, where M is the black hole mass. The radiative efficiency of accretion onto the black hole is ≲10^–3 for these sources, indicating that their accretion is advection-dominated.