Stellarlike Galactic Center excess challenges particle dark matter

The Galactic Center is potentially hosting the largest indirect signal from particle dark matter (DM), which in many well-motivated models would produce gamma rays as their final states. However, this region has often been dismissed for DM studies because of the evidence for an unexpected gamma-ray component over astrophysical backgrounds at GeV energies, firstly discovered in the data of the Large Area Telescope (LAT), the so-called Galactic Center excess (GCE). While this was initially considered to hint at GeV thermal relics, recent work supports a GCE interpretation in terms of a stellar population of millisecond pulsarlike sources in the Galactic bulge. Building on this preference, we reevaluate the Galactic Center as a powerful target for indirect DM searches via gamma rays. This is achieved by combining adaptive template fitting and photon-count statistical methods to assess the role of subthreshold point sources in the observed -LAT gamma-ray counts while minimizing the mismodeling of Galactic diffuse-emission backgrounds. In a fully self-consistent way, the gamma-ray data are fitted with a mixed model comprising a DM signal and a stellar bulge, both potentially contributing to the GCE. The space left for signals from weak-scale DM particle annihilations is quantified by extracting 95% confidence level upper limits on the annihilation cross section, which, depending on the DM density profile, result in stringent limits for masses ≲ 300 GeV . The robustness of our results is supported by tests on simulated data.