Applying Simulation-Based Inference to Spectral and Spatial Information from the Galactic Center Gamma-Ray Excess

The two most favored explanations of the Fermi Galactic Center gamma-rayexcess (GCE) are millisecond pulsars and self annihilation of the smooth darkmatter halo of the galaxy. In order to distinguish between these possibilities,we would like to optimally use all information in the available data, includingphoton direction and energy information. To date, analyses of the GCE havegenerally treated directional and energy information separately, or haveignored one or the other completely. Here, we develop a method for analyzingthe GCE that relies on simulation-based inference with neural posterior modelsto jointly analyze photon directional and spectral information while correctlyaccounting for the spatial and energy resolution of the telescope, here assumedto be the Fermi Large Area Telescope (LAT). Our results also have implicationsfor analyses of the diffuse gamma-ray background, which we discuss.