ON THE DISAPPEARANCE OF THE BROAD-LINE REGION IN LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

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 5 x 10(39) (M/10(7) M-circle dot)(2/3) erg s(-1), where M is the black hole mass. The radiative efficiency of accretion onto the black hole is less than or similar to 10(-3) for these sources, indicating that their accretion is advection-dominated.