Author(s): , , , , , , , ,
Institution(s): 1. Johns Hopkins University, 2. NASA Goddard Space Flight Center, 3. Northwestern University, 4. University of Crete , 5. University of Geneva, 6. University of Washington
High redshift galaxies permit the study of the formation and evolution of X-ray binary populations on cosmological timescales, probing a wide range of metallicities and star-formation rates. Here, I will present results from a large scale population synthesis study that models the X-ray binary populations from the first galaxies of the Universe until today. We use as input to our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. (2011) 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 and compared to the most recent Chandra surveys of distant galaxies, gives predictions about the global scaling of emission from X-ray binary populations with properties such as star-formation rate and stellar mass, and the evolution of these relations with redshift, as well as the evolution of the galaxy X-ray luminosity function with redshift. Our simulations show that the X-ray luminosity density (X-ray luminosity per unit volume) from X-ray binaries in our Universe today is dominated by low-mass X-ray binaries, and it is only at z>2.5 that high-mass X-ray binaries become dominant. We also find that there is a delay of ~1.1 Gyr between the peak of X-ray emissivity from low-mass Xray binaries (at z~2.1) and the peak of star-formation rate density (at z~3.1). The peak of the X-ray luminosity from high-mass X-ray binaries (at z~3.9), happens ~0.8 Gyr before the peak of the star-formation rate density, which is due to the metallicity evolution of the Universe. Finally, I will discuss the possible energy feedback of X-ray binaries in the re-ionization and thermal evolution of the Universe at early times, providing prescriptions for the X-ray binary feedback that can be directly incorporated into cosmological simulations.