Max Meier: Neutrinos at the Highest Energies: IceCube’s Window into Ultra-High-Energy Cosmic Rays

Tuesday 8 Dec 2026, 13:15 → 14:15 Europe/Stockholm

FB54 (AlbaNova Main Building)

Ultra-high-energy cosmic rays (UHECRs) produce astrophysical neutrinos (TeV+) inside their sources and so-called cosmogenic neutrinos (PeV+) on their journey through the universe. These neutrinos are unique messengers from the distant and violent universe, able to probe the sources of UHECRs. The IceCube Neutrino Observatory is the largest neutrino detector in the world, instrumenting a cubic kilometer of Antarctic   ice to catch these rare and elusive particles.

In this talk, after briefly reviewing IceCube’s recent studies of astrophysical neutrinos, I will present IceCube’s world leading limit on the neutrino flux at the highest energies. For the first time the non-observation of cosmogenic neutrinos puts serious constraints on the composition of UHECRs. I also put IceCube’s limit into context of the recent observation of an extremely-high-energy neutrino in KM3NeT.

Finally, in light of the recent discovery of a large population of little red dots in the high redshift universe in data of the James Webb Space Telescope (JWST), I will discuss a potential flux of cosmogenic neutrinos arising from these sources if they are capable of accelerating cosmic ray protons efficiently.

About the speaker: Maximilian Meier is an assistant professor at the International Center for Hadron Astrophysics of Chiba University. He received his PhD from TU Dortmund in 2019 searching for tau neutrinos using the IceCube detector. During his Postdoc at Chiba University, he was involved in construction and testing of optical modules (so-called D-Eggs) now deployed as part of the IceCube Upgrade.  His current research focuses on cosmogenic neutrinos, tau neutrinos and machine learning.

In the OKC: ELPA corridor C5 (AlbaNova)