Using the Fundamental Plane of Black Hole Activity to Distinguish X-ray Processes from Weakly Accreting Black Holes

Understand

The fundamental plane of black hole activity is a relation between X-ray luminosity, radio luminosity, and black hole mass for hard state Galactic black holes and their supermassive analogs.

• The fundamental plane suggests that, at low-accretion rates, the physical processes regulating the conversion of an accretion flow into radiative energy could be universal across the entire black hole mass scale.
• However, there is still a need to further refine the fundamental plane in order to better discern the radiative processes and their geometry very close to the black hole, in particular the source of hard X-rays.
• Further refinement is necessary because error bars on the best-fit slopes of the fundamental plane are generally large, and also the inferred coefficients can be sensitive to the adopted sample of black holes.