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arXiv · 1012.3678

Components of the Extragalactic Gamma Ray Background

Floyd W. Stecker·Tonia M. Venters
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Abstract

We present new theoretical estimates of the relative contributions of unresolved blazars and star-forming galaxies to the extragalactic gamma-ray background (EGB) and discuss constraints on the contributions from alternative mechanisms such as dark matter annihilation and truly diffuse gamma-ray production. We find that the Fermi source count data do not rule out a scenario in which the EGB is dominated by emission from unresolved blazars, though unresolved star-forming galaxies may also contribute significantly to the background, within order-of-magnitude uncertainties. In addition, we find that the spectrum of the unresolved star-forming galaxy contribution cannot explain the EGB spectrum found by EGRET at energies between 50 and 200 MeV, whereas the spectrum of unresolved FSRQs, when accounting for the energy-dependent effects of source confusion, could be consistent with the combined spectrum of the low-energy EGRET EGB measurements and the Fermi-LAT EGB measurements.

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Floyd W. Stecker, Tonia M. Venters. 2010-12-16. Components of the Extragalactic Gamma Ray Background. https://doi.org/10.1088/0004-637x/736/1/40

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