Ultra-High-Energy Cosmic Rays

A special issue of Universe (ISSN 2218-1997). This special issue belongs to the section "High Energy Nuclear and Particle Physics".

Deadline for manuscript submissions: closed (1 April 2025) | Viewed by 3218

Special Issue Editor


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Guest Editor
Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210033, China
Interests: high-energy neutrinos; ultra-high energy cosmic rays; high energy phenomena in the Universe

Special Issue Information

Dear Colleagues,

Ultra-high-energy cosmic rays (UHECRs) are particles from the Universe with energies above 1 EeV (1018 eV),extending up to beyond 100 EeV. These energies are much higher than those achieved by human-made accelerators. Such high energy particles, subsequently, are important probes to study acceleration physics, particle physics, and new physics beyond the standard models. However, how and where those particles are accelerated to such high energies still remains a mystery, even 60 years after they were discovered. As UHECRs travel to Earth, their paths are altered by magnetic fields, causing the observed UHECR directions to deviate from the directions of their sources. This discrepancy presents a challenge in pinpointing the origins of these cosmic rays. Decades of experimental and theoretical work have been dedicated to exploring this phenomenon. The world’s largest UHECR observatories, the Pierre Auger Observatory (PAO) and the Telescope Array (TA) experiments, have been measuring the spectrum, composition, and anisotropy of UHECRs for over a decade, providing us with more and more information to uncover the origin and acceleration mechanism of UHECRs. The development of next-generation experiments, such as the Giant Radio Array for Neutrino Detection (GRAND) project and the Square Kilometre Array (SKA), would further increase the statistics of observed UHECRs. Furthermore, the progress in multi-messenger astronomy enriches our knowledge further on features of source candidates, the extra-galactic background light, and the intergalactic and galactic magnetic field, developing our understanding of the acceleration and escape of UHECRs in the source, and their propagation from the source to Earth. This marks an exciting time, bringing us closer to understanding this scientific marvel.

The aim of this Special Issue is to collect the current knowledge from theories and observations on the physics of UHECRs and their source candidates, understanding our position in relation to, and what kind of efforts are needed to solve, this 60-year-old mystery.

Dr. Haoning He
Guest Editor

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Keywords

  • high energy neutrino
  • high energy gamma-ray
  • ultra-high-energy cosmic rays
  • particle acceleration
  • hadronic interactions
  • anisotropy
  • composition
  • multi-messenger astronomy
  • magnetic fields
  • Gamma-Ray Bursts (GRBs)
  • galaxy clusters
  • Active Galactic Nuclei (AGN)
  • Tidal Disruption Events (TDEs)
  • radio galaxies
  • starburst galaxies
  • pulsars

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Published Papers (3 papers)

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Research

11 pages, 1319 KiB  
Article
The Multimessenger Contribution of Ultra-High-Energy Cosmic Rays from Gamma-Ray Bursts
by Zhenjiang Li, Fangsheng Min, Yi Jin and Yiqing Guo
Universe 2025, 11(1), 22; https://doi.org/10.3390/universe11010022 - 15 Jan 2025
Viewed by 761
Abstract
It has long been debated whether gamma-ray bursts (GRBs) could serve as potential sources of ultra-high-energy cosmic rays (UHECRs). In this study, we consider GRBs as sources of UHECR injection with an injection index of α=2 and propagate them through the [...] Read more.
It has long been debated whether gamma-ray bursts (GRBs) could serve as potential sources of ultra-high-energy cosmic rays (UHECRs). In this study, we consider GRBs as sources of UHECR injection with an injection index of α=2 and propagate them through the extragalactic magnetic field within the framework of CRPropa 3. The baryon loading factor fCR is taken into account to quantify the rate of UHECR energy injection. In the benchmark case with a jet opening angle of θj=1 and fCR=1, we find that both high- and low-luminosity populations contribute to less than 10% of the UHECR spectrum. The most constrained scenario suggests fCR15, indicating that GRBs are less efficient in producing the all-sky UHECR intensity. The high-energy diffuse neutrinos and gamma rays resulting from interactions between UHECRs from GRBs and extragalactic background photons do not dominate the observations of Fermi-LAT or IceCube. Full article
(This article belongs to the Special Issue Ultra-High-Energy Cosmic Rays)
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12 pages, 4926 KiB  
Article
Radio Detection of UHE Cosmic Rays and Neutrinos off the Moon with Two 30 m Telescopes
by Linjie Chen, Jianli Zhang, Lihong Geng and Lingmei Cheng
Universe 2025, 11(1), 7; https://doi.org/10.3390/universe11010007 - 28 Dec 2024
Viewed by 574
Abstract
Due to the Askaryan effect, radio emissions will be produced when ultra-high-energy (UHE) cosmic rays and neutrinos impact the lunar regolith. Many experiments have been proposed and performed to detect such radio emissions from the lunar regolith. However, none of the Cherenkov radio [...] Read more.
Due to the Askaryan effect, radio emissions will be produced when ultra-high-energy (UHE) cosmic rays and neutrinos impact the lunar regolith. Many experiments have been proposed and performed to detect such radio emissions from the lunar regolith. However, none of the Cherenkov radio signals has been detected in these experiments up to now. In order to improve the detectability of the UHE particles, we proposed an experiment to carry out the radio observations of the UHE cosmic rays and neutrinos with two 30 m telescopes for a far longer time than the present experiments. The expected sensitivity for the detection of such UHE particles has been calculated, both for cosmic rays and neutrinos. The results show that a few UHE particle events above 1020 eV could be detected with the expected observation time of several thousand hours. Full article
(This article belongs to the Special Issue Ultra-High-Energy Cosmic Rays)
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10 pages, 3054 KiB  
Article
First Results of the CREDO-Maze Cosmic Ray Project
by Tadeusz Wibig, Michał Karbowiak, Punsiri Dam-O, Karol Jȩdrzejczak, Jari Joutsenvaara, Julia Puputti, Juha Sorri and Ari-Pekka Leppänen
Universe 2024, 10(9), 346; https://doi.org/10.3390/universe10090346 - 28 Aug 2024
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Abstract
The CREDO-Maze project is the concept for a network of stations recording local, extensive cosmic ray air showers. Each station consists of four small scintillation detectors and a control unit that monitors the cosmic ray flux 24 h a day and transmits the [...] Read more.
The CREDO-Maze project is the concept for a network of stations recording local, extensive cosmic ray air showers. Each station consists of four small scintillation detectors and a control unit that monitors the cosmic ray flux 24 h a day and transmits the results to the central server. The modular design of each array allows the results to be used in educational classes on nuclear radiation, relativistic physics, and particle physics and as a teaching aid in regular school classrooms and more. As an example, we present here some preliminary results from the CREDO-Maze muon telescope missions to the Arctic and down into a deep salt mine, as well as the first shower-particle correlation measurements from a table-top experiment at Walailak University. These experiments show that the different geometric configurations of the CREDO-Maze detector set can be used for projects beyond the scope of the secondary school curriculum, and they can form the basis of student theses and dissertations at universities. Full article
(This article belongs to the Special Issue Ultra-High-Energy Cosmic Rays)
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