Dissecting the Diffuse Emission of the Galaxy with the HAWC Observatory

Georg Schwefer

Published 2025-09-03Version 1

Galactic diffuse gamma-ray emission is produced by the interaction of high-energy cosmic rays propagating through the Milky Way with interstellar gas and radiation fields. Its measurement can provide crucial insights into the acceleration and transport of cosmic rays throughout our Galaxy. Here, we present a new analysis of the TeV Galactic diffuse gamma-ray emission using 8 years of HAWC data. This data was processed with the updated Pass 5 processing, enhancing the sensitivity and resolution of the instrument. For the analysis, we make use of Gammapy, an open-source package for gamma-ray astronomy, and recent models of the Galactic diffuse emission at TeV energies. After subtracting the emission from sources using an algorithm akin to that developed for the foreseen CTAO Galactic plane survey, we find significant remaining emission throughout the Galactic plane. We show the latitudinal and longitudinal flux profiles of the emission in multiple parts of the galaxy taking into account various sources of uncertainty and compare to existing models. We find significant emission beyond 3 degree latitude, consistent in shape with the prediction for the interaction of cosmic rays with the interstellar gas. We also demonstrate that our results are consistent with recent LHAASO results when equivalent analysis methods are used.