Unresolved Unidentified Source Contribution to the Gamma-ray Background

Abstract

The large majority of EGRET point sources remain without an identified low-energy counterpart, and a large fraction of these sources are most likely extragalactic. Whatever the nature of the extragalactic EGRET unidentified sources, faint unresolved objects of the same class must have a contribution to the diffuse extragalactic gamma-ray background (EGRB). Understanding this component of the EGRB, along with other guaranteed contributions from known sources, is essential if we are to use this emission to constrain exotic high-energy physics. Here, we follow an empirical approach to estimate whether a potential contribution of unidentified sources to the EGRB is likely to be important, and we find that it is. Additionally, we show how upcoming GLAST observations of EGRET unidentified sources, as well as of their fainter counterparts, can be combined with GLAST observations of the Galactic and extragalactic diffuse backgrounds to shed light on the nature of the EGRET unidentified sources even without any positional association of such sources with low-energy counterparts.

11 pages, 5 figures, submitted to ApJ

References in corpus (6)

• Gamma-Ray Luminosity Function of Blazars and the Cosmic Gamma-Ray Background: Evidence for the Luminosity Dependent Density Evolution
• Gamma rays from clusters of galaxies
• Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for GLAST
• The Likely Cause of the EGRET GeV Anomaly and its Implications
• Source population synthesis and the Galactic diffuse gamma-ray emission
• Unidentified EGRET Sources and the Extragalactic Gamma-Ray Background

Cited by in corpus (6)

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• The Extragalactic Background Light Absorption Feature in the Blazar Component of the Extragalactic Gamma-ray Background
• The detectability of dark matter annihilation with Fermi using the anisotropy energy spectrum of the gamma-ray background
• Separating astrophysical sources from indirect dark matter signals
• Extragalactic Gamma-ray Background from Star-forming Galaxies: Will Empirical Scalings Suffice?
• A luminosity constraint on the origin of unidentified high energy sources