PT Journal AU Ackermann, Mea Garcia Soto, A TI High-energy and ultra-high-energy neutrinos: A Snowmass white paper SO Journal of High Energy Astrophysics JI J. High Energy Astrophys. PY 2022 BP 55 EP 110 VL 36 DI 10.1016/j.jheap.2022.08.001 LA English AB Astrophysical neutrinos are excellent probes of astroparticle physics and high-energy physics. With energies far beyond solar, supernovae, atmospheric, and accelerator neutrinos, high-energy and ultrahigh-energy neutrinos probe fundamental physics from the TeV scale to the EeV scale and beyond. They are sensitive to physics both within and beyond the Standard Model through their production mechanisms and in their propagation over cosmological distances. They carry unique information about their extreme non-thermal sources by giving insight into regions that are opaque to electromagnetic radiation. This white paper describes the opportunities astrophysical neutrino observations offer for astrophysics and high-energy physics, today and in coming years. ER