Abstract
In the frame of unification schemes for radio-loud active galactic nuclei (AGNs), FR I radio galaxies are believed to be BL Lacertae (BL Lac) objects with the relativistic jet misaligned to our line of sight, and FR II radio galaxies correspond to misaligned radio quasars. The Ledlow-Owen dividing line for FR I/FR II dichotomy in the optical absolute magnitude of host galaxy-radio luminosity (M_R-L_Rad) plane can be translated to the line in the black hole mass-jet power (M_bh-Q_jet) plane by using two empirical relations: Q_jet-L_Rad and M_bh}-M_R. We use a sample of radio quasars and BL Lac objects with measured black hole masses to explore the relation of the jet power with black hole mass, in which the jet power is estimated from the extended radio emission. It is found that the BL Lac objects are clearly separated from radio quasars by the Ledlow & Owen FR I/II dividing line in the M_bh-Q_jet plane. This strongly supports the unification schemes for FR I/BL Lac object and FR II/radio quasar. We find that the Eddington ratios L_bol/L_Edd of BL Lac objects are systematically lower than those of radio quasars in the sample with a rough division at L_bol/L_Edd 0.01, and the distribution of Eddington ratios of BL Lac objects/quasars exhibits a bimodal nature, which imply that the accretion mode of BL Lac objects may be different from that of radio quasars.
Highlights
FR I radio galaxies have lower radio power than FR II galaxies (Fanaroff & Riley 1974)
The optical luminosity of the host galaxy can be converted to black hole mass Mbh by using the empirical relation (1), while the jet power Qjet can be estimated from the radio luminosity with relation (2)
It is found that BL Lacertae (BL Lac) objects can be roughly separated from quasars by the FR I/II dividing line
Summary
FR I radio galaxies (defined by edge-darkened radio structure) have lower radio power than FR II galaxies (defined by edge-brightened radio structure due to compact jetterminating hot spots) (Fanaroff & Riley 1974). Padovani & Urry (1992) derived the radio LFs of flat spectrum radio quasars (FSRQs) and FR II galaxies from a sample of radio-loud AGNs. The unified scheme of BL Lac objects and FR I radio galaxies have been extensively explored by many previous authors with different approaches, such as the comparisons of the spectral energy distributions (SEDs) in different wavebands (e.g., Owen et al 1996; Capetti et al 2000; Bai & Lee 2001), the radio morphology, the radio luminosity functions (LFs) (e.g., Padovani & Urry 1991; Kollgaard et al 1992; LaurentMuehleisen et al 1993) and the optical line emission (e.g., Marchã et al 2005).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
