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J. F. Dolan (Lab. for X-Ray Astrophysics, NASA GSFC)
X-ray pulses with millisecond-long FWHM have been detected in RXTE (Rossi X-Ray Timing Explorer) satellite observations of Cyg XR-1. Their identity as short-timescale variations in the X-ray luminosity of the source, and not stochastic variability in the X-ray flux, is established by their simultaneous occurrence and similar pulse structure in two independent energy bandpasses. The light-time distance corresponding to the timescale of their FWHM indicates that they originate in the inner region of the accretion disk around the system's black hole component. The fluence in the pulses can equal or exceed the fluence of the system's average continuous flux over the duration of the pulse's FWHM in several different bandpasses between 1 and 73 keV. Millisecond pulses are detected during both high and low luminosity states of Cyg XR-1, and during transitions between luminosity states.
The author(s) of this abstract have provided an email address for comments about the abstract: Joseph.F.Dolan@nasa.gov
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.