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

Understand

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.