Session D21: Cosmic Ray SIG Minisymposium

Live

This talk will address open business topics for the Cosmic Ray SIG and discuss them with the community. Please refer to the Physics of the Cosmos page for additional details [https://pcos.gsfc.nasa.gov/physpag/meetings/APS_2021/APS2021-agenda.php#crsig]   

Live

The origin of ultra-high-energy cosmic rays remains one of the big questions of astroparticle physics. Too rare for direct measurements in space, these cosmic rays are observed indirectly by particle cascades they induce when impinging the atmosphere. Modern ground-based experiments, such as the Pierre Auger Observatory and the Telescope Array, combine several detection techniques for these air showers, in particular, arrays of particle detectors and fluorescence telescopes. Recently, several arrays, such as IceTop and Auger, are also adding radio antennas to further increase the measurement accuracy. Moreover, balloon and space missions have the potential to provide unprecedented statistics at the highest energies. With recent observations of the cosmic-ray energy spectrum, mass composition, and a weak anisotropy in their arrival directions, we were able to restrict scenarios for their origin. Galactic cosmic rays seem to reach energies up to around 10$^1^8$ eV and extragalactic sources beyond 10$^2^0$ eV. Further progress requires, on the one hand, higher statistics and measurement accuracy for cosmic-ray protons and nuclei, and, on the other hand, multi-messenger techniques aiming for a direct discovery of cosmic-ray sources by photons and neutrinos.   

Live

Despite nearly 100 years since their first observations, little is still known about the sources of the cosmic rays at the end of the energy spectrum and the processes by which they are accelerated. At rates of $< 1$ / km$^2$ / century, detecting these particles and extracting information from them requires extremely large effective area detectors. In this talk I will present a concept for using radio detection of cosmic rays interacting in the Moon’s regolith from low lunar orbit to probe spectral recovery above the highest energies observed, spatial clustering to identify sources, and a channel for detection of secondary particles from the decay of hypothesized superheavy dark matter particles.   

Live

The Payload for Ultrahigh Energy Observations (PUEO) is a planned long-duration stratospheric balloon mission that will have world-leading sensitivity to fluxes of ultrahigh-energy (UHE, $>\sim10^{18}$ eV) neutrinos. PUEO will either make the first detection or set the best constraints on both cosmogenic neutrinos (produced during the propagation of UHE cosmic rays) and UHE neutrinos directly produced in astrophysical sources. PUEO consists of a $\sim$200-channel interferometric radio telescope pointed down at the Antarctic ice sheet in order to detect the impulsive Askaryan radio emission produced by UHE neutrinos interacting in the ice. PUEO is also sensitive to the radio emission from extensive air showers, typically induced by UHE cosmic rays, but also by in-air decays of tau leptons generated by UHE neutrino interactions in the Earth. PUEO is an evolution of the successful ANITA experiment, with key upgrades including a significantly lower-threshold digital beamforming trigger, a larger number of detection antennas, a dedicated low-frequency system for improved air shower detection, improved calibration systems, and more accurate orientation sensors. PUEO has been selected as a NASA Pioneers mission and is expected to launch in December 2024.   

Live

The highest energy cosmic rays and PeV astrophysical neutrinos are tantalizing multi-messengers from some of the most extreme energetic environments in the Universe. As a precursor for the Probe of Extreme Multi-Messenger Astrophysics (POEMMA), the Extreme Universe Space Observatory on a Super Pressure Balloon II (EUSO-SPB2) will use the calorimetric properties of atmosphere to target Ultra High Energy Cosmic Rays and search for signatures of astrophysical tau-neutrinos using the earth skimming technique. The EUSO-SPB2 science payload features an air Cherenkov telescope (CT) and a UV fluorescence telescope  (FT) each with 1 m diameter entrance pupils and Schmidt optics. With vantage points from the sub-orbital altitude of 33 km, EUSO-SPB2 will record EeV cosmic rays by looking down with the FT and also search for bright upward-going flashes from the dark ocean. The CT will look slightly below the Earth's limb to search for tau decay signatures and measure background signatures. Operation in an astrophysical target of opportunity mode is also planned. The first direct Cherenkov measurements of air showers from near space is also planned by looking slightly above the limb with the CT. The launch is planned from Wanaka NZ in 2023.   

Live

The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is designed to observe ultrahigh-energy cosmic rays (UHECRs) and cosmic neutrinos from space with sensitivity over the full celestial sky. Developed as a NASA Astrophysics Probe-class mission, POEMMA consists of two identical telescopes orbiting the Earth in a loose formation that observe extensive air showers (EAS) via air fluorescence and Cherenkov emissions. UHECRs and UHE neutrinos above 20 EeV are observed with the stereo fluorescence technique, while tau neutrinos above 20 PeV are observed via the optical Cherenkov signals produced by up-going EAS produced by the decay of Earth-emerging tau-leptons. The POEMMA satellites are designed to quickly re-orientate to follow up transient cosmic neutrino sources and obtain unparalleled neutrino flux sensitivity. Both observation techniques and the instrument design are being validated by current and upcoming missions, such as Mini-EUSO and EUSO-SPB as part of the JEM-EUSO program, and Terzina SmallSat mission. We will discuss the POEMMA science performance and the current roadmap to the POEMMA mission.