Invited Presentation

Fundamental Plane of Quiescent AGNs

Author(s): Fu-Guo Xie (SHAO) Feng Yuan (SHAO)

Presenter: Fu-Guo Xie (上海天文台)

We re-investigate the fundamental plane of quiescent AGNs, a relationship between radio and X-ray luminosities and BH mass.Yuan & Cui (2005) predicts that the radio/X-ray correlation index, \xi_X, changes from \xi_X = 0.6 to
\xi_X = 1.2-1.3 when L_X/L_Edd decreases below a critical value ~1E−6. While many works favor such a change, there are also several works claiming the opposite. We gather from literature a largest quiescent AGN (defined as L_X/L_Edd < 1E-6) sample to date, consisting of 75 sources. We find that these quiescent AGNs follow a \xi_X = 1.23 radio/X-ray relationship, in excellent agreement with the Yuan & Cui prediction. The reason for the discrepancy between the present result and some previous works is that their samples contain not only quiescent sources but also “normal” ones (i.e., L_X/L_Edd > 1E-6). In this case, the quiescent sources will mix up with those normal ones in LR and LX. The value of \xi_X will then be between 0.6 and 1.3, with the exact value
being determined by the sample composition, i.e., the fraction of the quiescent and normal sources. Based on this result, we propose that a more physical way to study the Fundamental Plane is to replace L_R and L_X with
L_R/L_Edd and L_X/L_Edd, respectively.