ar X iv : a st ro - p h / 01 03 15 7 v 2 1 3 Se p 20 01 Populations of X - ray binaries and the dynamical history of their host galaxies

The observed luminosity distributions of X-ray sources indicate the presence of several populations of X-ray binaries in the nearby galaxies. Each population has its formation and evolutionary history, depending on the host environment. The features seen in the log N(>S) – log S curves for different types of galaxies and for different galactic components can be reproduced by a birth-death model, in which the lifespans of the binaries are inversely proportional to their X-ray brightness. Conversely, the dynamical history of a galaxy can be inferred from the luminosity distributions of its X-ray binary populations.