We have studied the newly-discovered microquasar in NGC 7793 in radio , optical and X-ray bands .
This system comprises a large ( 250 \times 120 pc ) line-emitting optical nebula , detected in H \alpha and He II \lambda 4686 .
The optical nebula coincides with a synchrotron-emitting radio cocoon , with a radio luminosity about 4 times that of Cas A .
The central black hole appears as a hard X-ray source with a point-like , blue optical counterpart .
Two prominent radio lobes are located at the extremities of the cocoon .
Just ahead of the radio lobes , we found two X-ray hot spots , which we interpret as a signature of the bow shock into the interstellar medium .
The X-ray hot spots , radio lobes , X-ray core and major axis of the cocoon are well aligned , proving that the system is powered by a jet .
From the X-ray data , we estimate a jet power \sim a few \times 10 ^ { 40 } erg s ^ { -1 } , active over a timescale \approx 10 ^ { 5 } yrs .
This extraordinary system is a long-sought analog of the Galactic microquasar SS 433 .