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arXiv · 1506.05124

Evidence for Unresolved Gamma-Ray Point Sources in the Inner Galaxy

Samuel K. Lee·Mariangela Lisanti·Benjamin R. Safdi·Tracy R. Slatyer·Wei Xue
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Abstract

We present a new method to characterize unresolved point sources (PSs), generalizing traditional template fits to account for non-Poissonian photon statistics. We apply this method to Fermi Large Area Telescope gamma-ray data to characterize PS populations at high latitudes and in the Inner Galaxy. We find that PSs (resolved and unresolved) account for ~50% of the total extragalactic gamma-ray background in the energy range ~1.9 to 11.9 GeV. Within 10$^\circ$ of the Galactic Center with $|b| \geq 2^\circ$, we find that ~5-10% of the flux can be accounted for by a population of unresolved PSs, distributed consistently with the observed ~GeV gamma-ray excess in this region. The excess is fully absorbed by such a population, in preference to dark-matter annihilation. The inferred source population is dominated by near-threshold sources, which may be detectable in future searches.

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Samuel K. Lee, Mariangela Lisanti, Benjamin R. Safdi, Tracy R. Slatyer, Wei Xue. 2016-02-03. Evidence for Unresolved Gamma-Ray Point Sources in the Inner Galaxy. https://doi.org/10.1103/physrevlett.116.051103

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