Ascertain the origin of the Galactic Center GeV gamma-ray excess

Ascertain whether the Galactic Center GeV gamma-ray excess is produced by a population of unresolved millisecond pulsars or by the stellar bulge, in light of the complex background emission toward the Galactic center.

Background

The Galactic Center shows a distinct GeV gamma-ray excess whose spectrum and spatial distribution can be fit by certain dark matter annihilation models. However, due to complex diffuse backgrounds, the excess could also be explained by astrophysical sources such as unresolved millisecond pulsars or emission correlated with the stellar bulge.

In framing the motivation for their constraints on a separate 20 GeV halo excess, the authors note that the origin of the Galactic Center excess remains uncertain, emphasizing the need to discriminate among plausible astrophysical explanations.

References

However, because of the very complicated background emission in the direction of the Galactic center, it is unclear whether this excess is actually from a group of unresolved millisecond pulsars or even the stellar bulge.

— Constraining the dark matter origin of the halo-like 20 GeV $γ$-ray excess with the AMS-02 antiproton data  (2512.12176 - Wang et al., 13 Dec 2025) in Section 1, Introduction