Open Questions in Cosmic-Ray Research at Ultrahigh Energies
Open Questions in Cosmic-Ray Research at Ultrahigh Energies
We review open questions and prospects for progress in ultrahigh-energy cosmicray (UHECR) research, based on a series of discussions that took place during the "The High-Energy Universe: Gamma-Ray, Neutrino, and Cosmic-ray Astronomy" MIAPP workshop in 2018.Specifically, we overview open questions on the origin of the bulk of UHECRs, the UHECR …