XRB population synthesis models in 0<z<20 galaxies

In this paper, we present results from large-scale population synthesis models of binary populations in galaxies from z=0 to ~20. We use as input into our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. (2011MNRAS.413..101G) to self-consistently account for the star formation history (SFH) and metallicity evolution of each galaxy.

We run a grid of 192 models, varying all the parameters known from previous studies to affect the evolution of XRBs. We use our models and observationally derived prescriptions for hot gas emission to create theoretical galaxy X-ray luminosity functions (XLFs) for several redshift bins. Models with low common envelope efficiencies, a 50% twins mass ratio distribution, a steeper initial mass function exponent, and high stellar wind mass-loss rates best match observational results from Tzanavaris & Georgantopoulos, though they significantly underproduce bright early-type and very bright (L_x_>10^41^) late-type galaxies.