Building a Galactic Atlas of Potential Cosmic Ray Sources

Ultra-High-Energy Cosmic Rays (UHECRs), which constantly shower the Earth, are energetic particles (> 10^17 eV) produced by extreme cosmic phenomena. To aid the search for galactic accelerators, we developed the Galactic UHECR Atlas, a tool for generating arrival direction maps of hypothetical sources scattered around the Milky Way.

To build the Atlas, we used the CRPropa3 simulation framework to model UHECR propagation by back-propagating antiprotons from Earth through the Planck-tuned JF12 and base UF23 Galactic Magnetic Field (GMF) models. The simulations covered discrete energies between 200 PeV and 10 EeV. By cataloging particle intersections with a grid of observer spheres across the galaxy, we generated data for UHECRs produced at each grid point and observed at Earth. Our tool, published on GitLab with sample data, allows users to create custom sky maps from any combination of galactic sources with isotropic background noise. As a use case, we trained a convolutional neural network on these maps to identify single-source locations (see Nicolas San Martin’s poster). This contribution reports on the Atlas, what we have learned about possible UHECR source distributions from it, and planned future work.