ar X iv : a st ro - p h / 01 03 15 7 v 1 1 1 M ar 2 00 1 Population of X - ray binaries and the dynamical history of their host galaxies

The observed luminosity distributions of X-ray sources suggest the presence of several populations of X-ray binaries in the nearby galaxies. Each population probably has a different formation and evolutionary history, depending on the intrinsic properties of the sources and the host environment. The features seen in the Log N (> S) – Log S plots for different galactic components and for different types of galaxies can be reproduced by a simple population-evolutionary model, in which the life spans of the binaries are inversely proportional to their X-ray brightness. Conversely, the dynamical history of a galaxy can be inferred from the luminosity distribution of its X-ray binary populations.