The Fundamental Planes of Black Hole Activity for High-Synchrotron-Peaked BL Lacertae Objects

Abstract The radio–X-ray correlation and Fundamental Plane (FP) of black hole activity can serve as a diagnostic tool for the origin of X-ray emissions. There was a scaling relation between radio and X-ray emissions for High-synchrotron-peaked BL Lacertae objects (HBLs), i.e., $L_{\rm {R}}\propto L_{\rm {X}}^{0.64}$, which can be explained by ADAF-dominated mode or synchrotron cooling (Syn-c). However, many results of studying blazar physics show that the X-ray emissions of HBLs are mainly produ