Dark matter or millisecond pulsars? A deep learning-based analysis of the Fermi Galactic Centre Excess

Abstract

The \gammaγ-ray Galactic Centre Excess (GCE) remains one of the few observed high-energy signals for which a dark matter (DM) origin is a plausible explanation. We present a deep learning-based analysis of the \gammaγ-ray sky in the Galactic Centre region, carefully accounting for the mathematical degeneracy between faint point-sources (PSs) such as millisecond pulsars (MSPs) and DM-like Poisson emission. Using recent models for the Galactic foregrounds, we find that relatively few bright PSs just below Fermi’s detection threshold seem unlikely to explain the GCE, although we continue to find evidence for PSs. Looking ahead, further improvements in the modelling of the \gammaγ-ray sky will be crucial for distinguishing between a DM-like and point-like morphology of the signal.