The exploration of the universe has recently entered a new era thanks to the multi-
messenger paradigm, characterized by a continuous increase in the quantity and quality of …

High-energy cosmic rays are observed indirectly by detecting the extensive air showers
initiated in Earth's atmosphere. The interpretation of these observations relies on accurate …

The observation of electromagnetic radiation from radio to γ-ray wavelengths has provided a
wealth of information about the Universe. However, at PeV (10 15 eV) energies and above …

A high-energy neutrino event detected by IceCube on 22 September 2017 was coincident in
direction and time with a gamma-ray flare from the blazar TXS 0506+ 056. Prompted by this …

We report a measurement of the energy spectrum of cosmic rays for energies above 2.5× 10
18 eV based on 215,030 events recorded with zenith angles below 60. A key feature of the …

Abstract The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is designed to
accurately observe ultra-high-energy cosmic rays (UHECRs) and cosmic neutrinos from …

We report a measurement of the energy spectrum of cosmic rays above 2.5× 10 18 eV
based on 215 030 events. New results are presented: at about 1.3× 10 19 eV, the spectral …

The present white paper is submitted as part of the “Snowmass” process to help inform the
long-term plans of the United States Department of Energy and the National Science …

We review open questions and prospects for progress in ultrahigh-energy cosmic ray
(UHECR) research, based on a series of discussions that took place during the “The High …

We report a quasidifferential upper limit on the extremely-high-energy (EHE) neutrino flux
above 5× 10 6 GeV based on an analysis of nine years of IceCube data. The astrophysical …