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X‐Ray States and Radio Emission in the Black Hole Candidate XTE J1550−564

2001; IOP Publishing; Volume: 554; Issue: 1 Linguagem: Inglês

10.1086/321364

1538-4357

S. Corbel, P. Kaaret, Rajeev Kumar Jain, C. D. Bailyn, R. P. Fender, J. A. Tomsick, Emrah Kalemci, Vince McIntyre, D. Campbell‐Wilson, J. M. Mïller, Michael L. McCollough,

Astrophysics and Cosmic Phenomena

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 were conducted with the Australia Telescope Compact Array and 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 5 days after a transition to an intermediate/very high state, but we observed no radio emission 6 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 radio emission detected 5 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.