School of Physics Colloquium

What are the mysterious sources of the most energetic particles ever observed? What astrophysical sources produce very energetic neutrinos? How do particles interact at extreme energies? Building on the progress achieved by the ground-based observations we are developing space and sub-orbital missions to answer these questions. The Extreme Universe Space Observatory (EUSO) on a super pressure balloon (SPB) is designed to detect the highest energy astroparticles from above. EUSO-SPB1 flew in 2017 with a fluorescence telescope. EUSO-SPB2 is being built to observe both fluorescence and Cherenkov from ultrahigh and very high energy cosmic rays and neutrinos. These sub-orbital missions pave the way to space missions such as POEMMA, the Probe Of Extreme Multi-Messenger Astrophysics, a space mission designed to discover the sources of UHECRs and to observe neutrinos above 20 PeV from energetic transient events. EUSO-SPB2 and POEMMA will open new multi-messenger windows onto the most energetic events in the Universe, enabling the study of new astrophysics and particle physics at these extreme energies.