Discovery of a New Galactic Center Excess Consistent with Upscattered Starlight

Abstract

We present a new extended gamma ray excess detected with the Fermi Satellite Large Area Telescope toward the Galactic Center that traces the morphology of infrared starlight emission. Combined with its measured spectrum, this new extended source is approximately consistent with inverse Compton emission from a high-energy electron-positron population with energies up to about 10 GeV. Previously detected emissions tracing the 20 cm radio, interpreted as bremsstrahlung radiation, and the Galactic Center Extended emission tracing a spherical distribution and peaking at 2 GeV, are also detected. We show that the inverse Compton and bremsstrahlung emissions are likely due to the same source of electrons and positrons. All three extended emissions may be explained within the framework of a model where the dark matter annihilates to leptons or a model with unresolved millisecond pulsars in the Galactic Center.

13 pages and 5 figures. Version 2 was expanded to include tests to demonstrate the robustness of results against background systematics. Conclusions unchanged. Version 3 includes more checks and matches the published version

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Cited by in corpus (6)

• Millisecond pulsars and the Galactic Center gamma-ray excess: the importance of luminosity function and secondary emission
• A neural simulation-based inference approach for characterizing the Galactic Center $\gamma$-ray excess
• Dim but not entirely dark: Extracting the Galactic Center Excess' source-count distribution with neural nets
• Molecular Clouds as the Origin of the Fermi Gamma-Ray GeV-Excess
• Inverse Compton emission from millisecond pulsars in the Galactic bulge
• A Compound Poisson Generator approach to Point-Source Inference in Astrophysics