The Quasi-Periodic Oscillations and Low-Frequency Noise of Scorpius X-1 as Transient Chaos: A Dripping Handrail?

Jeffrey D. Scargle, Thomas Steiman-Cameron and Karl Young
Theoretical Studies Branch, Space Science Division
National Aeronautics and Space Administration, Ames Research Center

David L. Donoho
Deapartment of Statistics, Stanford Univeristy

James P. Crutchfield
Santa Fe Institute

James Imamura
Institute of Theoretical Science and Department of Physics
University of Oregon

Abstract

We present evidence that the quasi-periodic oscillations (QPO) and low frequency noise (LFN) characteristic of may accretion sources are different aspects of the same physical process. We analyzed a long, high time resolution EXOSAT observation of Sco X-1. The x-ray luminosity varies stochastically on time scales from milliseconds to hours. The nature of this variability- as quantified with both power spectrum analysis and a new wavelet technique, the scalegram- agrees well with the dripping handrail accretion model, a simple dynamical system which exhibits transient chaos. In this model both the QPO and LFN are produced by radiation from blobs with a wide size distribution, resulting from accretion and subsequent diffusion of hot gas, the density of which is limited by an unspecified instability to lie below a threshold.

Citation

J. D. Scargle, D. L. Donoho, J. P. Crutchfield, T. Steiman-Cameron, J. Imamura, and K. Young. "The Quasi-Periodic Oscillations and Very Low Frequency Noise of Scorpius X-1 as Transient Chaos: A Dripping Handrail?" Astrophys. J. Lett. 411 1993: L91-L94.

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