Inferring the morphology of the Galactic Center excess with Gaussian processes

作者：Edward Ramirez, Yitian Sun, Matthew R. Buckley, Siddharth Mishra-Sharma, Tracy R. Slatyer · 发表于：Physical review. D/Physical review. D. · 年份：2025 · DOI：10.1103/physrevd.111.063065 · 被引用次数：5 · 研究领域：Gamma-ray bursts and supernovae、Stellar, planetary, and galactic studies、Scientific Research and Discoveries

Descriptions of the Galactic Center using Fermi gamma-ray data have so far modeled the Galactic Center excess (GCE) as a template with fixed spatial morphology or as a linear combination of such templates. Although these templates are informed by various physical expectations, the morphology of the excess is a priori unknown. For the first time, we describe the GCE using a flexible, nonparametric machine learning model---the Gaussian process (GP). We assess our model's performance on synthetic data, demonstrating that the model can recover the templates used to generate the data. We then fit the Fermi data with our model in a single energy bin from 2--20 GeV (leaving a spectral GP analysis of the GCE for future work) using a variety of template models of diffuse gamma-ray emission to quantify our fits' systematic uncertainties associated with diffuse emission modeling. We interpret our best-fit GP in terms of GCE templates consisting of an Navarro-Frenk-White (NFW) squared template and a bulge component to determine which bulge models can best describe the fitted GP and to what extent the best-fit GP is described better by an NFW squared template versus a bulge template. The best-fit GP contains morphological features that are typically not associated with traditional GCE studies. These include a localized bright source at around $(\ensuremath{\ell},b)=(20\ifmmode^\circ\else\textdegree\fi{},0\ifmmode^\circ\else\textdegree\fi{})$ and a diagonal arm extending Northwest from the...