Related papers: Ultra High-Energy Cosmic Ray Observations

The Southern part of the Pierre Auger Observatory is nearing completion, and has been in stable operation since January 2004 while it has grown in size. The large sample of data collected so far has led to a significant improvement in the…

The recent discovery by the Pierre Auger collaboration of anisotropy in the arrival directions of the highest energy cosmic rays, correlated with the positions of nearby active galactic nuclei, encourages the search for counterpart TeV…

We measure the correlation between the arrival directions of the highest energy cosmic rays detected by the Pierre Auger Observatory with the position of the galaxies in the HI Parkes All Sky Survey (HIPASS) catalogue, weighted for their HI…

The origin of ultra high energy cosmic rays promises to lead us to a deeper understanding of the structure of matter. This is possible through the study of particle collisions at center-of-mass energies in interactions far larger than…

We argue that the data published by the Pierre Auger Collaboration (arXiv:0711.2256) disfavor at 99% confidence level their hypothesis that most of the highest-energy cosmic rays are protons from nearby astrophysical sources, either Active…

The sources of ultra-high energy cosmic rays (UHECRs) are still one of the main open questions in high-energy astrophysics. If UHECRs are accelerated in astrophysical sources, they are expected to produce high-energy photons and neutrinos…

We review open questions and prospects for progress in ultrahigh-energy cosmic ray (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…

The ultra-high-energy cosmic ray (UHECR) spectra measured by the Pierre Auger Observatory (Auger) and the Telescope Array (TA) agree very well below $10^{19.5}$ eV but differ significantly at higher energies. We show that these differences…

The highest energy cosmic rays, above the Greisen-Zatsepin-Kuzmin cut-off of cosmic ray spectrum, may be produced in decays of superheavy long-living X-particles. We conjecture that these particles may be produced naturally in the early…

Extensive simulations of the ultra-high energy cosmic ray (UHECR) propagation in the Galactic magnetic field (GMF) have been performed, and the results are presented. The use of different available models of the large-scale GMF and/or…

We briefly discuss some open problems and recent developments in the investigation of the origin and propagation of ultra high energy cosmic rays (UHECRs).

The energy spectrum of ultra-high energy cosmic rays above 10$^{18}$ eV is measured using the hybrid events collected by the Pierre Auger Observatory between November 2005 and September 2010. The large exposure of the Observatory allows the…

By a short tour through the exciting field of very high-energy and ultra high-energy cosmic rays studies, a brief review is given about the current questions approached, in particular by the KASCADE experiment and the Pierre Auger project.…

We have calculated the probability that the clustering of arrival directions of ultra-high energy cosmic rays (UHECRs) is consistent with a finite number of uniformly distributed proton sources. The case of a continuous source distribution…

We use a kinetic-equation approach to describe the propagation of ultra high energy cosmic ray protons and nuclei and calculate the expected spectra and mass composition at the Earth for different assumptions on the source injection spectra…

The HiRes Collaboration has recently announced preliminary measurements of the energy spectrum of ultra-high energy cosmic rays (UHECR), as seen in monocular analyses from each of the two HiRes sites. This spectrum is consistent with the…

Ultra-high energy cosmic rays interacting with the radiation fields in the universe cause electromagnetic cascades resulting in a flux of extragalactic gamma rays, detectable to some 100 GeV. Recent precise measurements of the extragalactic…

We will discuss the main relevant aspects of the physics of ultra high energy cosmic rays. After a short recap of the experimental evidences, we will review theoretical models aiming at describing the sources of these extremely energetic…

The Pierre Auger Observatory has a unique potential to search for ultra-high energy photons (above ~1 EeV). First experimental limits on photons were obtained during construction of the southern part of the Observatory. Remarkably, already…

One of the most challenging open questions regarding the origin of ultrahigh energy cosmic rays (UHECRs) deals with the shape of the source emission spectra. A commonly-used simplifying assumption is that the source spectra of the highest…