arXiv subjects

A. van Vliet

Publications and source records attributed to A. van Vliet.

3 recordsLinked to original sources

arXiv2020

White Paper: ARIANNA-200 high energy neutrino telescope

The proposed ARIANNA-200 neutrino detector, located at sea-level on the Ross Ice Shelf, Antarctica, consists of 200 autonomous and independent detector stations separated by 1 kilometer in a uniform triangular mesh, and serves as a pathfinder mission for the future IceCube-Gen2 project. The primary science mission of ARIANNA-200 is to search for sources of neutrinos with energies greater than 10^17 eV, complementing the reach of IceCube. An ARIANNA observation of a neutrino source would provide strong insight into the enigmatic sources of cosmic rays. ARIANNA observes the radio emission from high energy neutrino interactions in the Antarctic ice. Among radio based concepts under current investigation, ARIANNA-200 would uniquely survey the vast majority of the southern sky at any instant in time, and an important region of the northern sky, by virtue of its location on the surface of the Ross Ice Shelf in Antarctica. The broad sky coverage is specific to the Moore's Bay site, and makes ARIANNA-200 ideally suited to contribute to the multi-messenger thrust by the US National Science Foundation, Windows on the Universe - Multi-Messenger Astrophysics, providing capabilities to observe explosive sources from unknown directions. The ARIANNA architecture is designed to measure the angular direction to within 3 degrees for every neutrino candidate, which too plays an important role in the pursuit of multi-messenger observations of astrophysical sources.

astro-ph.IM↗

arXiv2016

Cosmic-ray energy spectrum and composition up to the ankle - the case for a second Galactic component

We have carried out a detailed study to understand the observed energy spectrum and composition of cosmic rays with energies up to ~10^18 eV. Our study shows that a single Galactic component with subsequent energy cut-offs in the individual spectra of different elements, optimised to explain the observed spectra below ~10^14 eV and the knee in the all-particle spectrum, cannot explain the observed all-particle spectrum above ~2x10^16 eV. We discuss two approaches for a second component of Galactic cosmic rays -- re-acceleration at a Galactic wind termination shock, and supernova explosions of Wolf-Rayet stars, and show that the latter scenario can explain almost all observed features in the all-particle spectrum and the composition up to ~10^18 eV, when combined with a canonical extra-galactic spectrum expected from strong radio galaxies or a source population with similar cosmological evolution. In this two-component Galactic model, the knee at ~ 3x10^15 eV and the second knee at ~10^17 eV in the all-particle spectrum are due to the cut-offs in the first and second components, respectively. We also discuss several variations of the extra-galactic component, from a minimal contribution to scenarios with a significant component below the ankle (at ~4x10^18 eV), and find that extra-galactic contributions in excess of regular source evolution are neither indicated nor in conflict with the existing data. Our main result is that the second Galactic component predicts a composition of Galactic cosmic rays at and above the second knee that largely consists of helium or a mixture of helium and CNO nuclei, with a weak or essentially vanishing iron fraction, in contrast to most common assumptions. This prediction is in agreement with new measurements from LOFAR and the Pierre Auger Observatory which indicate a strong light component and a rather low iron fraction between ~10^17 and 10^18 eV.

astro-ph.HE↗

arXiv2014

CRPropa: a public framework to propagate UHECRs in the universe

To answer the fundamental questions concerning the origin and nature of ultra-high energy cosmic rays (UHECRs), it is important to confront data with simulated astrophysical scenarios. These scenarios should include detailed information on particle interactions and astrophysical environments. To achieve this goal one should make use of computational tools to simulate the propagation of these particles. For this reason the CRPropa framework was developed. It allows the propagation of UHECRs with energies $\gtrsim$10$^{17}$ eV and secondary gamma rays and neutrinos. The newest version, CRPropa 3, reflects an efficient redesign of the code as well as several new features such as time dependent propagation in three dimensions, galactic magnetic field effects and improved treatment of interactions, among other enhancements.

astro-ph.IM↗