Flicker noise in accretion discs

An accretion disc with an alpha parameter fluctuating at different radii is considered. The relation between the alpha fluctuations and the resulting fluctuations of the accretion rate near the accreting body is obtained. Fluctuations of the accretion rate and, consequently, of the luminosity proved to be of the flicker-noise type provided that the characteristic time-scale of the alpha fluctuations is of the order of the local viscous time-scale, and that the fluctuations at different radial scales are uncorrelated.