Disk-Jet Connection in BL Lac Objects with Different Accretion Modes

Abstract

The maximal jet power can be extracted from a standard thin accretion disk/spinning black hole is calculated as a function of dimensionless accretion rate m (m = M/M-Edd). Comparing with the jet power derived from the extended radio luminosity, we find that the accretion disks in most BL Lac objects should not be standard accretion disks. It is found that a pure ADAF is too faint to produce the optical ionizing luminosity of BL Lac objects derived from their narrow-line luminosity. We propose that an ADAF is present in the inner region of the disk and it transits to a standard thin disk outside the radius R-tr in most BL Lac objects, i.e., ADAF+SD (standard disk) scenario. This scenario can explain both the jet power and optical ionizing continuum emission of these BL Lac objects. The inferred R-tr similar to 40 - 150 GM(bh)/c(2), if the disks are accreting at the rate m = 0.01.