Fermi Gamma-ray Space Telescope

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

B. R. Safdi
S. K. Lee, M. Lisanti, T. R. Slatyer, W. Xue

Abstract:

I will present a new method to characterize unresolved point sources (PSs), generalizing traditional template fits to account for non-Poissonian photon statistics. I will apply this method to Fermi gamma-ray data to characterize PS populations in the Inner Galaxy. I will show that in the energy range ?1.9 to 11.9 GeV and within 10 degrees of the Galactic Center with |b| > 2 degrees, ?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. I will comment on ongoing work to identify members of this new source population using gamma ray data along with input from other wavelengths.