Related papers: Energetic particles and high-energy processes in c…
We investigate the interactions of energetic hadronic particles (cosmic ray protons) with photons and baryons in protogalactic environments, where the target photons are supplied by the first generations of stars to form in the galaxy and…
One of the most striking astrophysical phenomena today is the existence of cosmic ray particles with energies in excess of 10^20 eV. While their presence has been confirmed by a number of experiments, it is not clear where and how these…
Galaxies at high redshifts with strong star formation are sources of high-energy cosmic rays. These cosmic rays interact with the baryon and radiation fields of the galactic environment via photo-pair, photo-pion and proton-proton processes…
The existence of cosmic ray particles up to the ultra-high energy limit (> 10^20 eV) is now beyond any doubt. The detection of cosmic particles with such energies imposes a challenge for the comprehension of their sources and nature. On one…
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…
A fundamental question that can be answered in the next decade is: WHAT IS THE ORIGIN OF THE HIGHEST ENERGY COSMIC PARTICLES? The discovery of the sources of the highest energy cosmic rays will reveal the workings of the most energetic…
Cosmic ray particles with energies in excess of 10**(20) eV have been detected. The sources as well as the physical mechanism(s) responsible for endowing cosmic ray particles with such enormous energies are unknown. This report gives a…
We study the deflection of ultra high energy cosmic ray protons in different models of the regular galactic magnetic field. Such particles have gyroradii well in excess of 1 kpc and their propagation in the galaxy reflects only the large…
Cosmic rays have been observed up to energies $10^8$ times larger than those of the best particle accelerators. Studies of astrophysical particles (hadrons, neutrinos and photons) at their highest observed energies have implications for…
A simple model is exhibited in which the remnant density of charged vortons is used to provide candidates for explaining the observed ultra high energy cosmic rays (above $10^{20}$ eV). These vortons would be accelerated in active galaxies…
More than 100 years after the discovery of cosmic rays and various experimental efforts, the origin of ultra-high energy cosmic rays (E > 100 PeV) remains unclear. The understanding of production and propagation effects of these highest…
The recent discoveries of several reliable events of high energy cosmic rays at an energy above 10^20 eV raise questions about their path through the nearby universe. The two analyses of the Haverah Park data set and the Akeno data set…
Cosmological filaments, galaxy clusters, and galaxies are magnetized reservoirs of cosmic rays (CRs). The exchange of CRs across these structures is usually modeled assuming that they remain charged and magnetically confined. At high…
High-energy cosmic rays can be accelerated in clusters of galaxies, by mega-parsec scale shocks induced by accretion of gas during the formation of large-scale structure, or by powerful sources harbored in clusters. Once accelerated, the…
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…
Several phenomena in high energy astrophysics have been recently related to clusters of galaxies and to cosmic ray interactions occurring inside these structures. In many of these phenomena the observable effects depend on the energy…
Galaxy properties correlate with their position within the cosmic web. While galaxies are observed in an environment today, they may have experienced different environments in the past. The environmental history, linked to pre-processing,…
Non-thermal particles and high-energy radiation can play a role in the dynamical processes in star-forming regions and provide an important piece of the multiwavelength observational picture of their structure and components. Powerful…
The most energetic particles ever detected exceed $10^{20}$ eV in energy. Their existence represents at the same time a great challenge for particle physics and astrophysics, and a great promise of providing us for a probe of the validity…
Cosmic rays with energies exceeding $10^{20}\eV$ have been detected. The origin of these highest energy cosmic rays remains unknown. Established astrophysical acceleration mechanisms encounter severe difficulties in accelerating particles…