ENERGY FEEDBACK FROM X-RAY BINARIES IN THE EARLY UNIVERSE

Journal Article · Sun Oct 20 04:00:00 EDT 2013 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/776/2/L31· OSTI ID:22215425

Fragos, T.; Zezas, A. ^[1]; Lehmer, B. D. ^[2]; Naoz, S. ^[3]

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1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
2. The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States)
3. Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z ∼ 20) until today. We estimate that X-ray emission from XRBs dominates over AGN at z ∼> 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by ∼4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of ∼300 Myr and then decreases gradually at later times, showing little variation for mean stellar ages ∼> 3 Gyr. Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

• OSTI ID: 22215425
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 776; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DISTANCE
EMISSION
ENERGY SPECTRA
FEEDBACK
GALAXIES
GALAXY NUCLEI
LUMINOSITY
MASS
MEAN FREE PATH
PHOTONS
RED SHIFT
SIMULATION
STAR EVOLUTION
STARS
UNIVERSE
X RADIATION