X-ray States of Black-Hole Binaries and Implications for the Mechanism of Steady Jets

RXTE and other high-energy observatories continue to probe the properties of stellar-size black holes and the physics of accretion using bright X-ray transients in the Galaxy. Progress has been made in recognizing that the three states of active accretion are related to different physical elements that may contribute radiation: the accretion disk, a jet, and a compact and radio-quiet corona. Each X-ray state offers potential applications for general relativity in the regime of strong gravity. The temporal evolution of X-ray states is displayed for a few representative black-hole systems. Radio investigations have shown conclusively that the hard X-ray state is associated with the presence of a steady radio jet. The three X-ray states can be synthesized with the “unified model for black hole binary jets” by Fender, Belloni, & Gallo (2004) to gain further insights into the disk:jet connection. The “jet line” appears to coincide with the hard limit of the SPL state. Furthermore there are broad power peaks in PDS that appear to be confined to intermediate and hard states where a jet is present. This suggests that broad power peaks exhibit temporal signatures of non-thermal processes that are related to the jet mechanism, rather than properties inherent to a standard accretion disk.