2020ApJ...892..116W

Here we discuss the jet production efficiency in a sample of 17 young radio galaxies with measured redshifts, kinematic ages, and nuclear X-ray fluxes, for which the observed luminosities of compact jets/lobes and accretion disks correspond to the same episode of AGN activity. For the targets, we analyze the available optical data, estimating the bolometric luminosities of the accretion disks L_bol, and the black hole masses; we also derive the minimum jet kinetic luminosities, P_j. With this information we investigate the distribution of our sample in the three-dimensional space of the accretion rate λ_Edd ≡ L_bol/L_Edd, the nuclear X-ray luminosity L_X considered here as a limit for the emission of the disk coronae, and P_j, expressing the latter two parameters either in the Eddington units, or in the units of the disk luminosity. We find that (i) the accretion rate λ_Edd in our sample is distributed within a narrow range λ_Edd ∼ 0.01-0.2; (ii) the normalized jet power P_j/L_Edd formally correlates with the accretion rate λ_Edd, with some saturation at the largest values λ_Edd > 0.05; (iii) the jet production efficiency η_jet≡P_j/{dot}M_accc² spans a range from η_jet <= 10^–3 up to ∼0.2 at maximum, which is below the level expected for magnetically arrested disks around maximally spinning black holes; and (iv) there is a diversification in η_jet on the hardness-intensity diagram L_X/L_bol - λ_Edd, with the jets being produced most efficiently during the high/hard states, and suppressed during the soft states.