Related papers: The GZK cutoff behind a Magnetized Universe
Cosmic ray events above $10^{20}$ eV are on the verge of confronting fundamental particle physics. The neutrino is the only candidate primary among established particles capable of crossing 100 Mpc intergalactic distances unimpeded. The…
Here is reviewed our current understanding of Galactic and extragalactic diffuse gamma-ray emission. The spectrum of the extragalactic gamma-ray background above 30 MeV can be well described by a power law with photon index s=2.1. In the…
We study signatures of a structured universe in the multi-pole moments, auto-correlation function, and cluster statistics of ultra-high energy cosmic rays above 10^19 eV. We compare scenarios where the sources are distributed homogeneously…
The intimate geometry of space-time is expected to suffer stochastic fluctuations as a result of quantum gravitational effects. These fluctuations may induce observable consequences on the propagation of high energy particles over large…
We investigate signatures that would be produced in the spectrum and sky distribution of UHECR by a population of the Galactic sources of high-energy protons in the energy range around 1~EeV, i.e., around the diffusive-to-ballistic…
Cosmic ray events above 10^19 eV have posed a fundamental problem for more than thirty years. Recent measurements indicate that these events do not show the features predicted by the GZK bound. The events may, in addition, display angular…
We study the diffusive escape of cosmic rays from a central source inside a galaxy cluster to obtain the suppression in the outgoing flux appearing when the confinement times get comparable or larger than the age of the sources. We also…
In this paper we review the main features of the observed Cosmic Rays spectrum in the energy range $10^{17} {\rm eV}~\div~10^{20} {\rm eV}$. We present a theoretical model that explains the main observed features of the spectrum, namely the…
The flux of cosmic rays beyond the GZK cutoff ($\sim 10^{20}$ eV) may be explained through their production by ultra high energy cosmic neutrinos, annihilating on the relic neutrino background, in the vicinity of our galaxy. This process is…
The recently published precise spectrum of cosmic ray protons from the Alpha Magnetic Spectrometer has been examined in some detail from the standpoint of a search for deviations from a smooth, simple, power law. We find a significant…
Extragalactic cosmic ray protons with an injection spectrum of the type $E^{-2.7}$ show a spectrum on earth with a dip due to the Bethe-Heitler pair production against the photons of the cosmic microwave background. The dip is produced in…
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…
The origin of ultra-high-energy cosmic rays (UHECRs) remains an open question. Extragalactic magnetic fields can modify their propagation and, at sufficiently low energies, suppress the observed flux through the magnetic horizon (MH)…
Cosmic rays in the energy range $10^{18.0}$ - $10^{18.5}$ eV are thought to have a light, probably protonic, composition. To study their origin one can search for anisotropy in their arrival directions. Extragalactic cosmic rays should be…
The flux of ultrahigh energy cosmic rays reaching the Earth is affected by the interactions with the cosmic radiation backgrounds as well as with the magnetic fields that are present along their trajectories. We combine the SimProp cosmic…
Recent experimental data from the Fly's Eye and the Akeno array seem to indicate significant structure in the ultrahigh energy cosmic ray spectrum above $10^{18}\eV$. A statistically significant dip has been established at about…
In the energy range from ~ 10^12 eV to ~ 10^15 eV, the Galactic cosmic ray flux has anisotropies both on large scales, with an amplitude of the order of 0.1%, and on scales between ~ 10 and ~ 30 degrees, with amplitudes smaller by a factor…
The observation of cosmic--ray events above the Greisen-Kuzmin-Zatsepin (GZK) cutoff of $\sim 5\times 10^{19}$ eV challenges orthodox modeling. We discuss a possible solution which uses standard hot Big Bang cosmology and Standard Model…
The all-sky surveys in gamma-rays by the imaging Compton telescope (COMPTEL) and the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory for the first time allows detailed studies of the extragalactic…
We present a detailed analytical study of the propagation of ultra high energy (UHE) particles in extragalactic magnetic fields. The crucial parameter which affects the diffuse spectrum is the separation between sources. In the case of a…