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arXiv · astro-ph/0611271

Unidentified EGRET Sources and the Extragalactic Gamma-Ray Background

V. Pavlidou·J. M. Siegal-Gaskins·C. Brown·B. D. Fields·A. V. Olinto
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Abstract

The large majority of EGRET point sources remain to this day without an identified low-energy counterpart. Whatever the nature of the EGRET unidentified sources, faint unresolved objects of the same class must have a contribution to the diffuse gamma-ray background: if most unidentified objects are extragalactic, faint unresolved sources of the same class contribute to the background, as a distinct extragalactic population; on the other hand, if most unidentified sources are Galactic, their counterparts in external galaxies will contribute to the unresolved emission from these systems. Understanding this component of the gamma-ray background, along with other guaranteed contributions from known sources, is essential in any attempt to use gamma-ray observations to constrain exotic high-energy physics. Here, we follow an empirical approach to estimate whether a potential contribution of unidentified sources to the extragalactic gamma-ray background is likely to be important, and we find that it is. Additionally, we comment on how the anticipated GLAST measurement of the diffuse gamma-ray background will change, depending on the nature of the majority of these sources.

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V. Pavlidou, J. M. Siegal-Gaskins, C. Brown, B. D. Fields, A. V. Olinto. 2006-11-08. Unidentified EGRET Sources and the Extragalactic Gamma-Ray Background. https://doi.org/10.1007/s10509-007-9456-1

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