EXTRAGALACTIC BACKGROUND LIGHT FROM HIERARCHICAL GALAXY FORMATION: GAMMA-RAY ATTENUATION UP TO THE EPOCH OF COSMIC REIONIZATION AND THE FIRST STARS

Journal Article · Fri May 10 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/768/2/197· OSTI ID:22126702

Inoue, Yoshiyuki ^[1]; Inoue, Susumu ^[2]; Kobayashi, Masakazu A. R. ^[3]; Makiya, Ryu; Totani, Tomonori ^[4]; Niino, Yuu ^[5]

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1. Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics, Stanford University and SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)
2. Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
3. Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan)
4. Department of Astronomy, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan)
5. Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

We present a new model of the extragalactic background light (EBL) and corresponding {gamma}{gamma} 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 {approx} 3-5, our predicted {gamma}{gamma} opacity is in general agreement for observed gamma-ray energy below 400/(1 + z) GeV, whereas it is a factor of {approx}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. The horizon energy at which the gamma-ray opacity is unity does not evolve strongly beyond z {approx} 4 and approaches {approx}20 GeV. The contribution of Population III stars is a minor fraction of the EBL 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. The detailed results of our model are publicly available in numerical form at http://www.slac.stanford.edu/{approx}yinoue/Download.html.

• OSTI ID: 22126702
• Journal Information: Astrophysical Journal, Vol. 768, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION
ANISOTROPY
ATTENUATION
BACKGROUND RADIATION
DUSTS
EVOLUTION
GALAXIES
GAMMA RADIATION
GAMMA SOURCES
GEV RANGE
LUMINOSITY
MICROWAVE RADIATION
OPACITY
RED SHIFT
STANFORD LINEAR ACCELERATOR CENTER
STARS
TELESCOPES
THOMSON SCATTERING
ULTRAVIOLET RADIATION