High-Energy Neutrinos in the Multi-Messenger Era: From Cosmic Accelerators to Fundamental Physics with Mainak Mukhopadhyay

The discovery of a diffuse astrophysical neutrino flux by IceCube has opened a new window onto the high-energy Universe, yet the origin of much of this emission remains unknown. Identifying the underlying sources requires connecting the physics of cosmic particle accelerators to their neutrino signatures and, increasingly, combining neutrino observations with information carried by photons and gravitational waves. In this talk, I will discuss how engine-driven astrophysical transients provide promising environments for high-energy neutrino production, and how detailed source modeling can connect their physical properties to observable multi-messenger signatures. I will then discuss strategies for identifying such populations through searches triggered by other messengers, particularly gravitational waves. Finally, I will turn the question around and ask what the emerging high-energy neutrino sky can teach us beyond the astrophysical sources themselves, highlighting how recent IceCube observations can test dark matter scenarios and provide new probes of particle physics. Together, these examples illustrate the growing role of high-energy neutrinos as both messengers of the most energetic environments in the Universe and probes of fundamental physics.

This lecture was made possible by the William C. Ferguson Fund.