The Disk-Jet Link and Unification of FSRQs, BL Lac Objects, and FR Radio Galaxies

Abstract

ABSTRACTWe study the relationship between the broad-line luminosity LBLR and the intrinsic Eddington accretion ratios for a sample of 17 flat-spectrum radio quasars (FSRQs), 16 BL Lac objects, and 11 FRI and nine FRII radio galaxies, for which the above data are available. We find the following results: (1) The broad-line luminosity correlates with the intrinsic Eddington accretion ratios for all sources, approximately with the form . (2) For 17 FSRQs and nine FRII radio galaxies LBLR also correlates with , again approximately with the form . (3) For 16 BL Lac objects and 11 FRI radio LBLR is also correlated with , however approximately with the form . Our results support the theory that the formation of the broad-line region is intrinsically connected to the existence of the cold accretion disk. They also support the unification model—that FSRQ unify with FRII radio galaxies, BL Lacs with FRI radio galaxies, and FSRQs with BL Lacs. (4) The experimental results together with the theoretical analysis show that for BL Lac objects, the τ is about 0.11 and the evaporation radius is about 200 Rschw. However, for FSRQs, we can find that the τ is about 0.11, which is consistent with the value used by L. Maraschi & F. Tavecchio in 2003 and obtain the corresponding α = 0.022 and an evaporation radius R∗ ≃ 2Rschw. It is interesting that the value of α which we derived is consistent with the constraints obtained by L. C. Starling Rhana and colleagues in 2004. In addition, the R∗ = 2Rschw seems to show that the black hole of FSRQ is the Kerr black hole. For this reason, these experimental results together with the theoretical analysis show that the model of disk for FSRQs and FRII radio galaxies seems to favor the description of the cold disk–hot inner flow transition as in the classical ADAF approach. However, for BL Lacs and FRI radio galaxies, the disk model seems to favor the model of disk evaporation due to conduction between the disk and accreting corona. Moreover, on the basis of the implication of observational result, one notes that FSRQs is dramatically different from BL Lacs in the evaporation mechanism and the position of the inner disk radius. Why should be that? One should see that FSRQs have larger intrinsic Eddington accretion ratios, but BL Lac objects have smaller intrinsic Eddington accretion ratios. In addition, using the partial correlation regression analysis method, we find that the broad-line luminosity (LBLR) correlates significantly with the radio core luminosity () and the coefficient of the best-fit linear regression equation of relation is very close to one for the same sample. The results support the model of a close link between accretion processes and relativistic jets. Finally, the unified and evolution model of FSRQs, BL Lac objects, FRI, and FRII radio galaxies is also discussed.