Rikard Enberg (Uppsala University): High energy neutrinos from astrophysical sources and atmospheric showers

Thursday 12 Feb 2026, 14:00 → 15:00 Europe/Stockholm

Title: High energy neutrinos from astrophysical sources and atmospheric showers
Speaker: Rikard Enberg
Affiliation: Uppsala University
Room: Å90101

Abstract:
The origin of the high-energy diffuse neutrino flux observed in neutrino telescopes such as IceCube and KM3NeT is not known. Most models for astrophysical neutrino generation assume that neutrinos are generated from decays of charged pions and kaons produced in collisions of accelerated protons with ambient photons in astrophysical sources such as active galactic nuclei (AGN), gamma ray bursts (GRBs) or other systems with relativistic jets.

High energy neutrinos are also observed coming from the atmosphere, generated by collisions of cosmic rays with atmospheric nuclei followed by decays of produced pions and kaons, similarly to neutrinos from astrophysical sources. In the atmospheric case, there is also a conjectured but not yet observed contribution from heavier quarks that can be produced in hadronic collisions but not in proton-photon collisions. These “prompt” neutrinos have a harder energy spectrum, because they are heavier and more short-lived leading to much less energy loss. They are expected to dominate the spectrum at the highest energies.

I will demonstrate that heavy quarks may be produced in astrophysical sources too, if there is a significant amount of hadronic matter in the source. These will again have a harder energy spectrum, and in addition, neutrinos from charmed mesons, which dominate, have a different flavor composition than neutrinos from pions. I will show examples of such processes in supernovae with choked jets (“slow-jet supernovae”), AGN and magnetar-driven supernovae, and I will discuss how the flavor composition of the neutrinos might give a way of observing the heavy quark component.