Related papers: High-energy Cosmic Rays
The propagation of cosmic iron nuclei with energies above 10^19 eV from their sources to the Galaxy is discussed by assuming that cosmic rays at ultra-high energies are of extragalactic origin. In extragalactic space, cosmic nuclei interact…
We propose that the knee in the cosmic ray spectrum at energies E ~ 10^{15.5} eV is due to "new physics", namely to a channel in the high energy (~ TeV in the CM) proton interactions hitherto unaccounted for in estimating the energies of…
The study of high energy cosmic rays is a diversified field of observational and phenomenological physics addressing questions ranging from shock acceleration of charged particles in various astrophysical objects, via transport properties…
Although cosmic rays were discovered 90 years ago, we do not know how and where they are accelerated. There is compelling evidence that the highest energy cosmic rays are extra-galactic -- they cannot be contained by our galaxy's magnetic…
The possibility for a self-consistent description of all the basic features of the observed cosmic ray spectra and primary composition variations in the energy range of $10^{15}\div 10^{20}$ eV within the Galactic origin scenario is…
Recent measurements of cosmic ray electron energy spectra suggest that above 10 GeV there may be deviations from a single power law spectrum. There are hints (ATIC) for a bump occurring between 100 GeV and 1TeV, meaning that there might be…
We analyze the possibility that the cosmic ray knee appears at an energy threshold where the proton-dark matter cross section becomes large due to new TeV physics. It has been shown that such interactions could break the proton and produce…
The sharp change in slope of the ultrahigh energy cosmic ray (UHECR) spectrum around 10^18.6 eV (the ankle), combined with evidence of a light but extragalactic component near and below the ankle and intermediate composition above, has…
Cosmic ray (CR) particles arrive at the top of the Earth's atmosphere at a rate of around 1000 per square meter per second. They are mostly ionized nuclei - about 90% protons, 9% alpha particles traces of heavier nuclei and approximately 1%…
Neutrinos from far away sources annihilating at the Z resonance on relic neutrinos may give origin to the ultrahigh-energy cosmic rays. Here we present predictions of this mechanism with relic neutrinos lighter than 1 eV, which do not…
The high-energy universe has revealed that energetic particles are ubiquitous in the cosmos and play a vital role in the cultivation of cosmic environments on all scales. Energetic particles in our own galaxy, galactic cosmic rays (GCRs),…
The search for the origin of cosmic rays is as active as ever, mainly driven by new insights provided by recent pieces of observation. Much effort is being channelled in putting the so called supernova paradigm for the origin of galactic…
The origin of galactic cosmic rays is one of the most interesting unsolved problems in astroparticle physics. Experimentally, the problem is attacked by a multi-disciplinary effort, namely by direct measurements of cosmic rays above the…
We have measured the cosmic ray spectrum at energies above $10^{17}$ eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric…
We consider the problem of the cosmic ray spectrum formation assuming that cosmic rays are produced by Galactic sources. The anomalous diffusion equation proposed in our recent papers is used to describe cosmic ray propagation in the…
High energy cosmic rays allow probing phenomena that are inacessible to accelerators. Observation of cosmic rays, presumebly protons, with energies beyond $4 \times 10^{19} eV$, the so-called Greisen-Zatsepin-Kuzmin (GZK) cut-off, give…
In view of recent developments attention is directed again at two aspects of the well known 'knee' in the cosmic ray energy spectrum at 3 PeV: the mass of the predominant particles at this energy and their source. It is inevitable in a…
Theoretical aspects of potential astrophysical sources of the highest energy cosmic rays are discussed, including their energy budget and some issues on particle escape and propagation. After briefly addressing AGN jets and GRBs, we…
We examine the question of the origin of the Galactic cosmic-rays (GCRs) in the light of the data available at the highest energy end of the spectrum. We argue that the data of the Pierre Auger Observatory and of the KASCADE-Grande…
The topological defect scenario of origin of the observed highest energy cosmic rays is reviewed. Under a variety of circumstances, topological defects formed in the early Universe can be sources of very massive particles in the Universe…