WoU-MMA: Tracking Cosmic-ray Dynamics in our Galaxy by Combining HAWC with Multi-Messenger Data

The High-Altitude Water Cherenkov Observatory (HAWC) is an array of hundreds of detector stations located on a very high plateau near the highest mountain in Mexico, Pico de Orizaba, also known as Citlaltépetl, which is Nahuatl and translates to star mountain. These detector stations capture the signals of the strongest form of light in the universe, gamma rays, as they zoom through the Earth’s atmosphere. The gamma rays, which are invisible to the human eye, reach Earth from parts of the Milky-Way Galaxy that are filled with gas clouds, exploding stars and their leftover subatomic material, cosmic dust, or black hole environments that shoot out jets of subatomic particles that move superfast, almost at the speed of light. The subatomic particles from these environments are called cosmic rays. The gamma rays the HAWC Observatory measures come from cosmic rays. The nature of cosmic rays prohibits observing them directly from a distant source. The goal of this project is to better understand how the cosmic rays are propelled to superfast speeds by studying the gamma-ray traces they leave behind. In this project, HAWC data will be used and combined with data from observatories that measure light from space at other frequencies and other space messengers like neutrinos. This will improve the understanding of cosmic-ray dynamics in the Milky-Way Galaxy by tracing cosmic-ray interactions with the interstellar medium that produce gamma rays. Existing software tools proven to work with HAWC data will be used as well as new machine learning algorithms explored. The focus will be on supernova remnant/molecular cloud complex surveys in the field-of-view of the HAWC Observatory, novel microquasar modeling, and the study of very extended gamma-ray emission phenomena like the galactic diffuse emission, the Northern Fermi Bubble, and passive molecular clouds. The ultimate goal is to obtain a more complete picture of cosmic-ray acceleration, propagation, and distribution in the Milky Way Galaxy. This project advances the objectives of "Windows on the Universe: the Era of Multi-Messenger Astrophysics", one of the 10 Big Ideas for Future NSF Investments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.