  Accreting black holes are thought to emit the bulk of their power in the
X-ray band by releasing the gravitational potential energy of the infalling
matter. At the same time, they are capable of producing highly collimated jets
of energy and particles flowing out of the system with relativistic velocities.
Here we show that the 10 solar mass black hole in the X-ray binary Cygnus X-1
is surrounded by a large-scale (about 5 pc in diameter) ring-like structure
that appears to be inflated by the inner radio jet. We estimate that in order
to sustain the observed emission of the ring, the jet of Cygnus X-1 has to
carry a kinetic power that can be as high as the bolometric X-ray luminosity of
the binary system. This result may imply that low-luminosity stellar mass black
holes as a whole dissipate the bulk of the liberated accretion power in the
form of `dark', radiatively inefficient relativistic outflows, rather than
locally in the X-ray emitting inflow.
