%0 Journal Article %T X-ray states and radio emission in the black hole candidate XTE J1550-564 %A S. Corbel %A P. Kaaret %A R. K. Jain %A C. D. Bailyn %A R. P. Fender %A J. A. Tomsick %A E. Kalemci %A V. McIntyre %A D. Campbell-Wilson %A J. M. Miller %A M. L. McCollough %J Physics %D 2001 %I arXiv %R 10.1086/321364 %X We report on radio and X-ray observations of the black hole candidate (BHC) XTE J1550-564 performed during its 2000 X-ray outburst. Observations have been conducted with the Australia Telescope Compact Array (ATCA) and have allowed us to sample the radio behavior of XTE J1550-564 in the X-ray Low Hard and Intermediate/Very High states. We observed optically thin radio emission from XTE J1550-564 five days after a transition to an Intermediate/Very High state, but we observed no radio emission six days later, while XTE J1550-564 was still in the Intermediate/Very High state. In the Low Hard state, XTE J1550-564 is detected with an inverted radio spectrum. The radio emission in the Low Hard state most likely originates from a compact jet; optical observations suggest that the synchrotron emission from this jet may extend up to the optical range. The total power of the compact jet might therefore be a significant fraction of the total luminosity of the system. We suggest that the optically thin synchrotron radio emission detected five days after the transition to the Intermediate/Very High state is due to a discrete ejection of relativistic plasma during the state transition. Subsequent to the decay of the optically thin radio emission associated with the state transition, it seems that in the Intermediate/Very High state the radio emission is quenched by a factor greater than 50, implying a suppression of the outflow. We discuss the properties of radio emission in the X-ray states of BHCs. %U http://arxiv.org/abs/astro-ph/0102114v1