Hysteretic behavior and coherence of the black hole candidate X-ray binaries

Abstract

It is shown that transitions between the hard/low state and the soft/high state are determined not only by the rate of the accreting matter onto the black hole but also by the history of the matter accretion, i.e. the transitions show the hysteresis just as the magnetic materials do. We found also that in the soft/high state of GS1124-683, coherence of time variability is small between different energy X-rays and that the coherence depends on the fraction of the soft power law component. This is quite different from what is observed in the hard/low state of Cyg X-1 and GX339-4, where the coherence between different energy X-rays is near unity over a wide range of frequencies.