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

We present evidence that the quasi-periodic oscillations (QPO) and low frequency noise (LFN) characteristic of many 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 new wavelet technique, the {\it scalegram} - agrees well with the {\it dripping handrail} accretion model, a simple dynamical system which exhibits {\it 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.