X-ray binary evolution across cosmic time

In this paper, we present results from a large-scale population synthesis study that models the XRB populations from the first galaxies of the universe until today. We use as input to our modeling the Millennium II cosmological simulation (Boylan-Kolchin et al. 2009MNRAS.398.1150B) and the updated semi-analytic galaxy catalog by Guo et al. (2011MNRAS.413..101G) to self-consistently account for the star formation history and metallicity evolution of the universe.

Our modeling, which is constrained by the observed X-ray properties of local galaxies, gives predictions about the global scaling of emission from XRB populations with properties such as SFR and stellar mass, and the evolution of these relations with redshift. Our simulations show that the X-ray luminosity density (X-ray luminosity per unit volume) from XRBs in our universe today is dominated by low-mass XRBs, and it is only at z>~2.5 that high-mass XRBs become dominant.