Observational Evidence For The Cause Of The `Parallel Track' Phenomenon And Hysteresis Of Spectral Transitions In X-ray Binaries
Abstract
RXTE observations of neutron star LMXBs have shown the same kHz QPO frequency or the same X-ray color occurs at different X-ray fluxes in a single source, forming the so-called `parallel track' phenomenon. Hysteresis effect of spectral transitions, which is usually seen in black hole or neutron star soft X-ray transients, corresponds to the special cases of the phenomenon when the X-ray colors transit between two main spectral branches. Our systematic studies of the spectral state transitions seen in bright X-ray binaries with the RXTE/ASM and the Swift/BAT in the past 4-5 years indicates that the rate-of-change of the mass accretion rate dominates over the mass accretion rate itself in causing spectral state transitions, implying the rate-of-change of the mass accretion rate, an indicator of the non-stationary accretion in X-ray binaries, is the cause of both phenomena. Spectral and timing evidence will be provided in the presentation.
- Publication:
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AAS/High Energy Astrophysics Division #11
- Pub Date:
- March 2010
- Bibcode:
- 2010HEAD...11.4236Y