Discovery of a New Galactic Center Excess Consistent with Upscattered Starlight

TL;DR

This paper reports a new gamma ray excess at the Galactic Center, consistent with inverse Compton scattering from high-energy electrons, and explores its possible origins including dark matter or millisecond pulsars.

Contribution

It identifies a new gamma ray excess aligned with starlight emission and links it to inverse Compton processes, proposing potential dark matter or pulsar sources.

Findings

Detection of a new gamma ray excess aligned with infrared starlight

Evidence that inverse Compton and bremsstrahlung emissions originate from the same electron population

Possible explanations include dark matter annihilation or unresolved millisecond pulsars

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.