X-ray luminosity function of low-mass X-ray binaries in galaxies
  X-ray luminosity function derived from observations of X-ray sources in galactic bulges can be explained by prinicipal evolutionary relations for mass accretion rate onto the compact object. The observed mean distribution of individual X-ray luminosities of galactic LMXB is satisfactorily described by a symmetric quasi-Lorentzian curve. The flux variance for bright sources is found to be proportional to the mean luminosity. Such a distribution does not change the slope of the power law luminosity function of the source population, which is expected from the dependence of the mass transfer rate on the mass of the Roche-lobe filling non-degenerate optical component. 
K.A.Postnov (1,2), A.G.Kuranov (1) ((1) Sternberg Astronomical   Institute, Moscow, (2) University of Oulu, Finland)