log(M_BH)–log(L_bol) plane, with R shown as coloured dots (see colour bar at right). The black rectangle shows the region where the PCA was evaluated. The black solid and dotted arrows represent the direction of the strongest correlation as in Fig. 7. The dash-dotted line marks a constant λ_Edd = 0.2, representing the average value of the sample, while the magenta arrow shows the direction expected if the increase in R were driven uniquely by the decrease in λ_Edd.