[Previous] | [Session 83] | [Next]
M.P. Rupen, R.M. Hjellming (NRAO), A.J. Mioduszewski (Sydney University), V. Dhawan (NRAO)
We present an overview of on-going VLA observations of X-ray transients, ranging from initial detections of new sources like XTE J1118+480 to the late-time (quiescent?) behavior of old favorites like V404 Cyg. One basic conclusion is that the onset of radio emission, generally in the form of relativistic jet emission, is essentially related to a change in the state of the accretion disk, as revealed by a significant change in the X-ray flux or hardness. What happens afterwards is much less clear, but a few additional features are beginning to emerge. First, many radio flares (after the initial onset of activity) take place without obvious X-ray counterparts, as if, once the conditions in the disk are set up for radio activity, realtively minor (unobservable) fluctuations can lead to substantial recurrent radio emission. Second, radio flares often come in close pairs, although the two events may be quite different in character. Third, those sources which produce multiple long-lived jet ejections always send their ejecta out along roughly the same path, even if those ejection events are separated by many years. Finally, the same source can produce both long-lived relativistic radio jets, and basically stationary emission. Why this should be, and the relationship between the two, is not at all clear.