Towards a unified description of the jet-accretion coupling in stellar and super massive black holes

Radio and X-ray flux from accreting stellar-mass black holes in the low/hard state display a tight non-linear correlation from the 'quiescent' regime up to the transition to the high/soft state. The non-linearity of the correlation naturally leads to the possibility of a 'jet dominated' power output from these systems. In such a state most of the accretion power is dissipated in the form of bulk kinetic energy of the outflow, while a standard disc-corona system may still be responsible for the radiated luminosity. With the introduction of a mass correction, the same radio/X-ray scaling has been shown to apply in super massive black holes at the centre of active galactic nuclei. Expanding on this, we have found that the same sample of AGN exhibits a 'quenching' of the radio emission at about 10 per cent of the Eddington rate, just as seen in high/soft state black hole binaries. This result indicates that the same spectral phenomenology, and therefore probably jet-accretion coupling, is shown by stellar and super massive black holes and strengthens the notion of 'quiescence' as a very low luminosity version of the standard low/hard state.