We show that the radio emission of black hole (BH) and neutron star (NS)
X-ray binaries (XRBs) follows the analytical prediction of a jet model where
the jet carries a constant fraction of the accretion power. The radio emission
can therefore be used as a tracer of the accretion rate. This measure is
normalised with efficiently radiating objects. As it is independent of the
X-ray fluxes, the measure allows us to compare the accretion rate dependency of
the bolometric X-ray luminosity of BHs and NSs. For NSs, it scales linearly
with accretion rate while the scaling for BHs is quadratic - as expected for
inefficient accretion flows. We find the same behaviour in AGN. This new
approach uses the jet power to obtain the accretion rate. Thus, we know both
the jet power and the radiated power of an accreting BH. This allows us to show
that some accretion power is likely to be advected into the black hole, while
the jet power dominates over the bolometric luminosity of a hard state BH.Comment: conference proceedings of the Sixth Microquasar workshop:
Microquasars and Beyond, 18-22 September 2006 in Como, Italy (eds: T. Belloni
et al. 2006
