We study a stochastic variability of SS 433 in the 10 ^ { -4 } -5 \times 10 ^ { -2 } Hz frequency range based on RXTE data , and on simultaneous observations with RXTE and optical telescopes .
We find that the cross-correlation functions and power spectra depends drastically on the precession phase of the supercritical accretion disc .
When the wind funnel of the disc is maximally open to the observer , a flat part emerges in the power spectrum ; a break is observed at the frequency 1.7 \times 10 ^ { -3 } Hz , with a power-law index \beta \approx 1.67 at higher frequencies .
The soft emission forming mostly in the jets , lags behind the hard and optical emission .
When the observer does not see the funnel and jets ( the ‘ edge-on ’ disc ) , the power spectrum is described by a single power-law with \beta \approx 1.34 and no correlations between X-ray ranges are detected .
We investigated two mechanisms to explain the observed variability at the open disc phase , 1 ) reflection of radiation at the funnel wall ( X-rays and optical ) and 2 ) the gas cooling in the jets ( X-rays only ) .
The X-ray variability is determined by the contribution of both mechanisms , however the contribution of the jets is much higher .
We found that the funnel size is ( 2 - 2.5 ) \times 10 ^ { 12 } cm , and the opening angle is \vartheta _ { f } \sim 50 ^ { \circ } .
X-ray jets may consist of three fractions with different densities : 8 \times 10 ^ { 13 } , 3 \times 10 ^ { 13 } and 5 \times 10 ^ { 11 } cm ^ { -3 } , with most of the jet ’ s mass falling within the latter fraction .
We suppose that revealed flat part in the power spectrum may be related to an abrupt change in the disc structure and viscous time-scale at the spherization radius , because the accretion disc becomes thick at this radius , h / r \sim 1 .
The extent of the flat spectrum depends on the variation of viscosity at the spherization radius .