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arXiv · 0704.2888

The Extragalactic Gamma Ray Background

Charles D. Dermer
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Abstract

One way to understand the nonthermal history of the universe is by establishing the origins of the unresolved and truly diffuse extragalactic gamma rays. Dim blazars and radio/gamma galaxies certainly make an important contribution to the galactic gamma-ray background given the EGRET discoveries, and previous treatments are reviewed and compared with a new analysis. Studies of the gamma-ray intensity from cosmic rays in star-forming galaxies and from structure formation shocks, as well as from dim GRBs, are briefly reviewed. A new hard gamma-ray source class seems required from the predicted aggregate intensity compared with the measured intensity.

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Charles D. Dermer. 2007-05-10. The Extragalactic Gamma Ray Background. https://doi.org/10.1063/1.2757282

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