Related papers: Was the Highest Energy Cosmic Ray a Photon?
This paper summarizes the status and the recent measurements from the Pierre Auger Observatory. The energy spectrum is described and its features discussed. We report searches for anisotropy of cosmic ray arrival directions on large scales…
The Pierre Auger Observatory has conducted measurements of the energy spectrum and mass composition of cosmic rays using different methods. Utilizing both surface and fluorescence detectors (SD and FD), the Observatory provides…
We give an outline of possible extragalactic explanations of the highest energy cosmic ray events. We give a classification of the possible particles which could have caused the events and try to find suitable sources for each class. In…
The mass composition of ultra-high-energy cosmic rays is an open problem in astroparticle physics. It is usually inferred from the depth of the shower maximum (Xmax) of cosmic-ray showers, which is only ambiguously determined by modern…
Extensive air showers are the result of billions of particle reactions initiated by single cosmic rays at ultra-high energy. Their characteristics are sensitive both to the mass of the primary cosmic ray and to the fine details of hadronic…
The wealth of data collected in the last few years thanks to the Pierre Auger Observatory and recently to the Telescope Array made the problem of the origin of ultra high energy cosmic rays a genuinely experimental/observational one. The…
The nature and origin of ultra-high energy (UHE: reffering to > 10^19 eV) cosmic rays are great mysteries in modern astrophysics. The current theories for their explanation include the so-called "top-down" decay scenarios whose main…
We apply statistical inference on the Pierre Auger Open Data to discern for the first time the full mass composition of cosmic rays at different energies. Working with longitudinal electromagnetic profiles of cosmic ray showers, in…
A method is developed to search for air showers initiated by photons using data recorded by the surface detector of the Auger Observatory. The approach is based on observables sensitive to the longitudinal shower development, the signal…
Active galaxies and gamma ray bursts are the sources of the highest energy photons detected by astronomical telescopes. We speculate that they may be the sources of the highest energy cosmic rays. This makes them true proton accelerators,…
Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with $E \geq 6 \cdot 10^{19}$ eV by analyzing…
In this work the ultra high energy cosmic ray events recorded by the AGASA experiment are analysed. With detailed simulations of the extensive air showers initiated by photons, the probabilities are determined of the photonic origin of the…
The Pierre Auger Observatory is designed to elucidate the origin and nature of Ultra High Energy Cosmic Rays using a hybrid detection technique. A first run of data taking with a prototype version of both detectors (the so called…
Here we discuss the latest developments in the debate, where the ultrahigh energy cosmic ray particles come from. In this brief review, we emphasize the predictions that necessarily follow from the various concepts proposed. We discuss both…
Space-based experiments, either orbiting the Earth or from scientific balloon altitudes, measure high-energy cosmic rays by measuring from above the atmosphere the optical and radio signals generated by extensive air showers (EAS). These…
The study of ultra high energy cosmic rays is a very important scientific problem. It is likely to have a huge impact in our understanding of the universe. Very high energy particles have been observed to hit the Earth whose origin is…
Extensive air showers initiated by ultra-high energy cosmic rays are sensitive to the details of hadronic interactions models, so we present the main results obtained using the data of the Pierre Auger Observatory. The depth at which the…
The Pierre Auger Observatory is a facility designed for the study of ultra-high energy cosmic rays. The Observatory combines two different types of detectors: a surface array of 1600 water Cherenkov stations placed on a 1.5 km triangular…
Astrophysical flares are one of the possible prominent source classes of ultra-high-energy (UHE, $E > 10^{17}$ eV) cosmic rays, which can be detected by recording clusters of extensive air showers in arrays of detectors. The search for…
We present a brief introduction to the physics of Ultra High Energy Cosmic Rays (UHECRs), concentrating on the experimental results obtained so far and on what, from these results, can be inferred about the sources of UHECRs.