Related papers: High energy cosmic-ray interactions with particles…
On geological timescales, the Earth is likely to be exposed to an increased flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. Typical cosmic ray energies…
The Pierre Auger Observatory has been designed to investigate the most energetic particles known, the ultra high energy cosmic rays. The observatory, covering an area of 3000 km^2, combines two different detection techniques to study the…
The Sun is a bright source of GeV gamma rays, due to cosmic rays interacting with solar matter and photons. Key aspects of the underlying processes remain mysterious. The emission in the TeV range, for which there are neither observational…
Orbiting $\gamma$-detectors combined with the magnetic field of the Earth or the Sun can work parasitically as cosmic axion telescopes. The relatively short field lengths allow the axion-to-photon conversion to be coherent for $m_{axion}…
Contrary to expectations, several cosmic ray events with energies above $10^{20}$ eV have been observed. The flux of such events is well above the predicted Greisen-Zatsepin-Kuzmin cutoff due to the pion production (via the $\Delta$…
A new approach to investigations of ultra-high energy cosmic rays based on the ground-level measurements of the spectra of local density of EAS muons at various zenith angles is considered. Basic features of the local muon density…
In a recently proposed model the cosmic rays spectrum at energies above 10^{18} eV can be fitted with a minimal number of unknown parameters assuming that the extragalactic cosmic rays are only protons with a power law source spectrum…
Due to the coherence of all the protons in a nucleus, there are very strong electromagnetic fields of short duration in relativistic heavy ion collisions. They give rise to quasireal photon-photon and photon-nucleus collisions with a large…
Cosmic rays interacting with the Earth's atmosphere generate extensive air showers, which produce Cherenkov, fluorescence and radio emissions. These emissions are key signatures for detection by ground-based, sub-orbital, and…
High energy cosmic rays "illuminate" the Sun and produce an image that could be observed in up to five different channels: a cosmic ray shadow (whose energy dependence has been studied by HAWC); a gamma ray flux (observed at $E\le 200$ GeV…
Suppose that even the highest energy cosmic rays (CRs) observed on Earth are protons accelerated in local Milky Way Galaxy sources, with few if any from more distant sources. In this paper we treat the problem that supernovae remnants…
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,…
The field of ultra-high energy cosmic rays made a lot of progresses last years with large area experiments such as the Pierre Auger Observatory, HiRes and the Telescope Array. A suppression of the cosmic ray flux at energies above…
We discuss the possibility of observing distant accelerators of ultra high energy cosmic rays in synchrotron gamma rays. Protons propagating away from their acceleration sites produce extremely energetic electrons during photo-pion…
The IceCube experiment recently detected the first flux of high-energy neutrinos in excess of atmospheric backgrounds. We examine whether these neutrinos originate from within the same extragalactic sources as ultrahigh-energy cosmic rays.…
The results of a study of the cosmic ray composition in individual events in the energy range (2-12.5) EeV using the muon correlation method is presented. The considered sample included showers with zenith angles less than 60 degrees…
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…
We calculate the fluxes of neutrinos and gamma rays from interactions of cosmic rays with interstellar matter in our galaxy. We use EPOS-LHC, SIBYLL and GHEISHA to obtain the yield of these particles in proton, helium and iron collisions at…
Ultrahigh energy neutrons and pions are likely to be produced in particle interactions inside cosmic ray sources and subsequently decay to neutrinos and other secondary particles ($\pi^\pm \rightarrow \mu^\pm\nu_\mu(\bar \nu_\mu),\mu^\pm…
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…