in Proc. of the 1st GLAST Symposium, Feb 5-8, 2007, Stanford, AIP, Eds. S. Ritz, P. F. Michelson, and C. Meegan
astro-ph/0704.2888

For a PDF version of the article, click here.

THE EXTRAGALACTIC gamma RAY BACKGROUND

Charles D. Dermer


Space Science Division, Code 7653, Naval Research Laboratory
Washington, DC 20375-5352, USA


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.


Keywords: gamma-rays - blazars - background radiations
PACS: 95.85.Pw, 98.54.Cm, 98.62.Nx, 98.70.Rz, 98.70.Vc


Table of Contents

INTRODUCTION

BLAZARS AND RADIO / gamma GALAXIES

STAR-FORMING GALAXIES

CLUSTERS OF GALAXIES

GAMMA RAY BURSTS

ADDITIONAL CONTRIBUTIONS

REFERENCES

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