Extragalactic Very-High-Energy gamma-ray background

Abstract

We study the origin of the extragalactic diffuse gamma-ray background using the data from the Fermi telescope. To estimate the background level, we count photons at high Galactic latitudes |b|>60 degrees. Subtracting photons associated to known sources and the residual cosmic ray and Galactic diffuse backgrounds, we estimate the Extragalactic Gamma-ray Background (EGB) flux. We find that the spectrum of EGB in the very-high-energy (VHE) band above 30 GeV follows the stacked spectrum of BL Lacs. LAT data reveal the positive (1+z)^k, 1<k<4 cosmological evolution of the BL Lac source population consistent with that of their parent population, FR I radio galaxies. We show that EGB at E>30 GeV could be completely explained by emission from unresolved BL Lacs if k~3.

8 pages, 6 figures, accepted to Astrophysics Journal

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Cited by in corpus (13)

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• Minimal Cosmogenic Neutrinos
• Statistics of gamma-ray point sources below the Fermi detection limit
• Diffuse $\gamma$-ray emission from unresolved BL Lac objects
• Gamma-Ray Constraints on Maximum Cosmogenic Neutrino Fluxes and UHECR Source Evolution Models
• Cosmic Ray Models
• A minimal model for extragalactic cosmic rays and neutrinos
• Unified model for cosmic rays above $10^{17}$ eV and the diffuse gamma-ray and neutrino backgrounds
• Galactic diffuse gamma-ray emission at TeV energy
• Characterising the signatures of star-forming galaxies in the extra-galactic $\gamma$-ray background
• Very-high-energy gamma-ray emission from high-redshift blazars
• A new model for the extragalactic gamma-ray background
• New limit on high Galactic latitude PeV gamma-ray flux from Tibet AS-gamma data