paper

X-ray Spectral States and High-Frequency QPOs in Black Hole Binaries

arXiv:astro-ph/0510699 · doi:10.1002/asna.200510415

Abstract

The high-frequency quasi-periodic oscillations in the X-ray emission of black hole binaries and candidates are briefly examined with respect to the question of X-ray states. We use the prescription of McClintock and Remillard (2005), in which X-ray spectra and power density spectra are used to differentiate three main states of active accretion: "thermal", "hard", and "steep power-law". For the sources that exhibit pairs of HFQPOs with frequencies that scale in a 3:2 ratio, the QPO detections are associated with the steep power-law state. Furthermore, there is a clear trend in which the oscillation at twice the fundamental frequency is seen when the source has high X-ray luminosity, while the QPO at three times the fundamental frequency is seen at lower luminosity.

4 pages, 2 figures, Nordita Proceedings, Astron. Nachr. vol. 326

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