Related papers: Has the GZK suppression been discovered?
The primary cosmic rays particles with energies above 10**20 eV have been observed at many extensive air shower arrays since the beginning of observations over 40 years ago. The validity of measurements of signal s(600) used as energy…
A new method to derive an upper limit on photon primaries from small data sets of air showers is developed which accounts for shower properties varying with the primary energy and arrival direction. Applying this method to the…
Based on a newly proposed mirror-matter model of neutron-mirror neutron ($n-n'$) oscillations, the puzzles related to ultrahigh-energy cosmic rays (UHECRs) are explained. In particular, the phenomena around the Greisen-Zatsepin-Kuzmin (GZK)…
Ultra-high energy cosmic rays can propagate diffusively in cosmic magnetic fields. When their propagation time is comparable to the age of the universe, a suppression in the flux relative to the case in the absence of magnetic fields will…
The Yakutsk array observes the Cherenkov light emitted by UHECR in atmosphere. Recently, an autonomous subarray is added consisting of photomultipliers to measure the showers in the knee region. Our aim is to analyze the combined data set…
Existing small, medium and large arrays for the study of cosmic rays of ultra-high energies are aimed for obtaining information about our galaxy and extragalactic space, namely to search and study astronomical objects that produce the flux…
We compare the expected contribution of FR-II hot spots to the ultra-high energy cosmic ray spectrum (Rachen & Biermann 1993, A&A in press, BB paper astro-ph/9301010) to improved experimental results. We introduce a "world data set" of UHE…
Ultra-high energy photons constitute one of the most important pieces of the astroparticle physics problems. Their observation may provide new insight on several phenomena such as supermassive particle annihilation or the GZK effect.…
The suggestion is made that air showers with energies beyond the Greisen-Zatsepin-Kuz'min spectral cut-off may have primary vertices some 6 km lower in height than those of proton initiated showers with energies below the GZK cut-off. This…
An anisotropy signal for the arrival directions of ultra-high energy cosmic rays (UHECR) of more than 99% confidence level was established using data collected by the Pierre Auger Observatory. Cosmic rays with energy above $\sim 6 \times…
It is argued that if extragalactic magnetic fields are smaller than 2x10^{-12} G the flux of ultra-high energy photons of (a few)x10^{-1} eV cm^{-2}s^{-1}sr^{-1} predicted in the top-down models of UHE CR implies similar flux of the diffuse…
The origin of the highest energy cosmic rays is still unknown. At present, the major uncertainties are located at energies above $\sim 10^{19.5}$ eV, the expected beginning of the GZK suppression. This is mainly due to the low statistics…
The existence of cosmic rays of energies exceeding 10^20 eV is one of the mysteries of high energy astrophysics. The spectrum and the high energy to which it extends rule out almost all suggested source models. The challenges posed by…
Diffuse ultrahigh energy gamma-radiation can arise from a variety of astrophysical sources, including the interaction of extremely high energy cosmic rays with the 3K microwave background radiation or the collapse of topological defects…
We present the results of a search for cosmic ray point sources at energies above 10^19 eV in the HiRes stereo data set. The analysis is based on a maximum likelihood ratio test using the probability density function for each event rather…
We report on a search for extremely-high energy neutrinos with energies greater than $10^6$ GeV using the data taken with the IceCube detector at the South Pole. The data was collected between April 2008 and May 2009 with the half completed…
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…
Cosmic rays of energies larger than the Greisen-Zatsepin-Kuzmin (GZK) cutoff may be neutrinos if they acquire strong interactions due to a ``precocious unification'' of forces. A scenario for this to happen is outlined. There is no…
In this report we review the important progress made in recent years towards understanding the experimental data on ultra-high-energy ($E \gtrsim 10^9$ GeV) cosmic rays. We begin with a general survey of the available data, including a…
UHE neutrinos may transfer highest cosmic-rays energies overcoming $2.75K^\circ$ BBR and radio-waves opacities (the GZK cut off) from most distant AGN sources at the age of the Universe. These UHE $\nu$ might scatter onto those (light and…