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Title: Extragalactic background light from hierarchical galaxy formation. Gamma-ray attenuation up to the epoch of cosmic reionization and the first stars

Here, we present a new model of the extragalactic background light (EBL) and corresponding γγ opacity for intergalactic gamma-ray absorption from z = 0 up to z = 10, based on a semi-analytical model of hierarchical galaxy formation that reproduces key observed properties of galaxies at various redshifts. Including the potential contribution from Population III stars and following the cosmic reionization history in a simplified way, the model is also broadly consistent with available data concerning reionization, particularly the Thomson scattering optical depth constraints from Wilkinson Microwave Anisotropy Probe (WMAP). In comparison with previous EBL studies up to z ~ 3-5, our predicted γγ opacity is in general agreement for observed gamma-ray energy below 400/(1 + z) GeV, whereas it is a factor of ~2 lower above this energy because of a correspondingly lower cosmic star formation rate, even though the observed ultraviolet (UV) luminosity is well reproduced by virtue of our improved treatment of dust obscuration and direct estimation of star formation rate. Moreover, the horizon energy at which the gamma-ray opacity is unity does not evolve strongly beyond z ~ 4 and approaches ~20 GeV. The contribution of Population III stars is a minor fraction of the EBLmore » at z = 0, and is also difficult to distinguish through gamma-ray absorption in high-z objects, even at the highest levels allowed by the WMAP constraints. Nevertheless, the attenuation due to Population II stars should be observable in high-z gamma-ray sources by telescopes such as Fermi or the Cherenkov Telescope Array and provide a valuable probe of the evolving EBL in the rest-frame UV. Our detailed results of our model are publicly available in numerical form at« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [4]
  1. Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology
  2. Max Planck Inst. for Nuclear Physics, Heidelberg (Germany); Univ. of Tokyo (Japan). Inst. for Cosmic Ray Research
  3. Ehime Univ., Matsuyama (Japan). Research Center for Space and Cosmic Evolution
  4. Kyoto Univ. (Japan). Dept. of Astronomy
  5. National Astronomical Observatory of Japan, Mitaka (Tokyo). Optical and Infrared Astronomy Division
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0004-637X; arXiv:1212.1683
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 768; Journal Issue: 2
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States