The compact jet of the black hole candidate XTE J1550-564 during the 2000 X-ray outburst.

We report on radio, near-infrared, optical and X-ray observations of the black hole candidate (BHC) XTE J1550-564 performed during its 2000 X-ray outburst. These observations have allowed us to sample the behavior of XTE J1550-564 in the X-ray Low Hard and Intermediate/Very High states. The radio emission in the Low Hard state most likely originates from a compact jet and the synchrotron emission from this jet may extend up to the optical range or beyond, therefore indicating that the total power of the compact jet is a significant fraction of the total luminosity of the system. In the Intermediate/Very High state the radio emission is quenched, implying a suppression of the outflow. We discuss the properties of radio emission in the X-ray states of BHCs. [ABSTRACT FROM AUTHOR]