Upper Limit on the Cosmological Gamma-ray Background

Abstract

We show that the current extragalactic gamma-ray background (EGB) measurement below 100 GeV sets an upper limit on EGB itself at very high energy (VHE) above 100 GeV. The limit is conservative for the electromagnetic cascade emission from VHE EGB interacting with the cosmic microwave-to-optical background radiation not to exceed the current EGB measurement. The cascade component fits the measured VHE EGB spectrum rather well. However, once we add the contribution from known source classes, the Fermi VHE EGB observation exceeds or even violates the limit, which is approximated as E^2dN/dE < 4.5x10^-5 (E/100 GeV)^-0.7 MeV/cm^2/s/sr. The upper limit above 100 GeV is useful in the future to probe the EGB origin and the new physics like axion-like particles and Lorentz-invariance violation.

8 pages, 8 figures, accepted for publication in PRD, Interested readers may wish to consult the recent paper by Murase, Beacom and Takami (arXiv:1205.5755)

References in corpus (11)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data
• The Cosmic Infrared Background Resolved by Spitzer. Contributions of Mid-Infrared Galaxies to the Far-Infrared Background
• Very-High-Energy Gamma Rays from a Distant Quasar: How Transparent Is the Universe?
• GZK Neutrinos after the Fermi-LAT Diffuse Photon Flux Measurement
• The Fermi-LAT high-latitude Survey: Source Count Distributions and the Origin of the Extragalactic Diffuse Background
• Spitzer 70-micron Source Counts in GOODS-North
• Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of cosmic gamma-ray background
• Inspecting absorption in the spectra of extra-galactic gamma-ray sources for insight into Lorentz invariance violation
• The Cosmic MeV Gamma-ray Background and Hard X-ray Spectra of Active Galactic Nuclei: Implications for the Origin of Hot AGN Coronae
• BL Lac Contribution to the Extragalactic Gamma-Ray Background

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