The power spectra as a probe of some physical features of X-ray binaries

We have simulated, using a Monte Carlo method, intensity time series representing the time behaviour of some high mass X ray binaries. Taking into account some physical models of the accretion processes, we have parametrized different physical conditions on the source. The resulting time series have been analysed by Fast Fourier Transform techniques. Using different sets of parameters we have been able to generate power spectra of different shapes. Some preliminary results of these simulations and a comparison with an observed spectrum of a galactic X ray binary are discussed.