A STATISTICAL STUDY OF THE 164 DAY CLOCK NOISE OF THE RELATIVISTIC BEAMS IN SS-433

We have estimated the epochs of the phases of maximal red and blue beam Doppler shifts for various cycles of the approximately 164d period in SS 433, using an updated optical spectroscopic data base, which covers a time span of over 13 years. By constructing power density spectra of phase residuals based on these epochs (residuals measured relative to a hypothetical clock with constant period), we are able to characterize the statistical behavior of the clock noise in both the red and blue beam 164d cycles as a white noise process in the first time derivative of 164d phase fluctuations (i.e., as a white noise process in frequency, or equivalently, as a random walk in 164d phase). Our characterizations of the 164d clock noise in SS 433 show a strong, quantitative similarity to the previously characterized clock noise of the 35d periodicity of x-ray turn-ons in Her X-1, lending further credence to the notion that the relevant underlying physical process in both systems is disk precession.