Andrea Merloni (MPA)
We have recently examined the disc--jet connection in stellar mass and supermassive black holes by investigating the properties of their compact emission in the hard X-ray and radio bands. The log-linear correlation found between the radio and the X-ray luminosity and the black hole mass (the so-called "fundamental plane of black hole activity") can be used to extend the standard unification by orientation scheme to encompass, for the first time, a rigorous quantitative unification by mass and accretion rate. The orientation of the plane itself can be used to better constrain the nature of the accretion mode of low-luminosity black hole binaries and AGN. On the other hand, sources are observed to deviate significantly from the fundamental plane relation at high accretion rates, a clear indication of a transition to a different mode of accretion. Finally, the scatter about the plane can be used to put constrain on the amount of relativistic beaming in different AGN populations.