2014MNRAS.437.1187Z

Using an updated population synthesis code initially developed by Hurley et al., we modelled the synthetic X-ray binary (XRB) populations for direct comparison with the universal, featureless X-ray luminosity function (XLF) of high-mass X-ray binaries (HMXBs) in star-forming galaxies. Our main goal is to use the universal XLF to constrain the model parameters, given the current knowledge of binary evolution. We find that the one-dimensional (1D) Maxwellian velocity dispersion of the natal kick can be constrained to be of the order of σkick ∼ 150km/s, supporting earlier findings that neutron stars formed in binaries seem to receive significantly smaller natal kicks than the velocities of Galactic single pulsars would indicate. The super-Eddington accretion factor is further confirmed in the framework of stellar mass black holes (BHs), revealing that the true origin of most of the ultraluminous X-ray sources (ULXs) may indeed be the high-luminosity extension of ordinary HMXBs which harbour stellar mass BHs rather than exotic intermediate-mass BHs or ones. We present the detail properties of the model-predicted present-day HMXBs, which may be investigated by future high-resolution X-ray and optical observations of sources in nearby star-forming galaxies.