HEAD 2003 Meeting
Session 46. X-ray Binaries and Cataclysmic Variables II
Oral, Wednesday, March 26, 2003, 9:00-10:00am

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[46.04] Timing Atoll Sources

S. van Straaten, M. van der Klis (University of Amsterdam), R. Wijnands (University of St. Andrews)

We studied the correlated X-ray spectral and timing behaviour of the atoll sources 4U 0614+09 and 4U 1728-34 and demonstrate that the frequencies of the variability components of these two sources follow a universal scheme of correlations relatively independent of source luminosity. Most frequencies, from 0.1 to 1200 Hz, vary in a strongly correlated fashion, but one is nearly constant near 150 Hz. The transient source 4U 1608-52, previously classified as an atoll source but recently reported to trace a Z track in the color diagram, is found by us to exactly conform to this same universal atoll frequency correlation scheme, suggesting a very similar accretion flow configuration. A similar study of the millisecond X-ray pulsar SAX J1808.4-3658 is currently in progress, which indicates that some discrepancies occur in that source, perhaps related to a stronger magnetic field or a different spin in the pulsar as compared to the other atoll sources.

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Bulletin of the American Astronomical Society, 35#2
© 2003. The American Astronomical Soceity.