Multi-messenger models of neutrino sources in the extreme universe

Neutrinos offer a unique view into the extreme Universe: they travel unimpeded across cosmic distances and trace the most energetic astrophysical phenomena, revealing regions of the Universe invisible to traditional telescopes. Yet the origin of the high-energy neutrinos observed by IceCube, the world’s largest neutrino observatory, remains unknown. This project develops a novel multi-messenger framework to identify the source populations responsible, by combining theoretical models with observations of the three astrophysical messengers neutrinos, gamma rays, and cosmic rays. By fitting entire source populations to multi-messenger data, the project provides a new method to constrain the nature of cosmic neutrino sources. These efforts will advance our understanding of the high-energy Universe and the resulting tools will support the next generation of astroparticle research.