Exploring GeV - TeV gamma-ray emission from supernova remnants with the threeML framework

Supernova remnants (SNRs) have long been hypothesized as a source of Galactic Cosmic Rays, and some of them have indeed been shown to accelerate protons to at least TeV energies. Measurements of non-thermal emission in the gamma-ray regime are essential to determine the acceleration efficiencies, species of accelerated particles, and maximum acceleration energies of SNRs.

The High-Altitude Water Cherenkov observatory (HAWC) has been surveying the northern TeV gamma-ray sky for more than five years, while the Large Area Telescope (LAT) aboard the Fermi observatory has collected almost 15 years of data on the GeV gamma-ray sky. Combining data from both instruments is necessary to unlock the data’s full potential and to understand the high-energy emission from SNRs. However, lack of standardization as well as unique features of each instrument can make this a challenging and time-consuming task. ThreeML, the multi-mission maximum likelihood framework, is a python-based software package for multi-wavelength data analysis with a special focus on high-energy astronomy. Its flexible, plugin-based structure enables the inclusion of data from many different observatories in their diverse native formats without much additional effort by the user. Recent improvements to the fermipy-plugin within the threeML framework enable the analysis of Fermi-LAT data of Galactic sources with this software. I will present the status of the threeML framework, emphasizing recent developments. I will show how multi-mission spectral analyses, combining data from HAWC and Fermi-LAT, can improve our understanding of particle acceleration in SNRs.