Recent observations with the large air shower arrays of ultra high energy cosmic rays (UHECR) and recent measurements/estimates of the redshifts of gamma ray bursts (GRBs) seem to rule out extragalactic GRBs as the source of the cosmic rays that are observed near Earth, including those with the highest energies. Subject headings: cosmic rays; gamma rays bursts

Cosmic rays scatter off magnetic irregularities (Alfvén waves) with which they are resonant, that is, waves of wavelength comparable to their gyroradii. These waves may be generated either by the cosmic rays themselves, if they stream faster than the Alfvén speed, or by sources of MHD turbulence. Waves excited by streaming cosmic rays are ideally shaped for scattering, whereas the scattering ef...

There is evidence that cosmic rays were present in galaxies at moderately high redshift. This suggests that magnetic fields were also present. If cosmic rays and magnetic fields must always be close to equipartition, as they are to an order of magnitude within the local universe, this would provide a powerful constraint on theories of the origin and evolution of magnetic fields in galaxies. We ...

In this talk I present resent results on high energy cosmic rays, including energy spectra, composition and the study of arrival directions of cosmic ray primaries. Some related results in gamma-ray astronomy and selected recent advances in theory are also covered. c ⃝ Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. The ques...

We investigate the problem of transition from galactic cosmic rays to extragalactic ultra high energy cosmic rays. Using the model for extragalactic ultra high energy cosmic rays and observed all-particle cosmic ray spectrum, we calculate the galactic spectrum of iron nuclei in the energy range 108 − 109 GeV. The flux and spectrum predicted at lower energies agree well with the KASCADE data. Th...

The isotropic component of the γ-ray flux between 100MeV and 100EeV (10 eV) contains important information about the origin of highest energy cosmic rays and the extragalactic magnetic field (EGMF). Using numerical simulations of extragalactic cosmic and γ-ray propagation we show that an average fraction of ≃ 10% γ-rays in the total cosmic ray flux around 10EeV would imply both a non-accelerati...

We present new observations of the isotopic composition of low-energy He, C, N, 0, and Ne nuclei. The observations cover the energy interval from ,...., 5 to 30 MeV per nucleon, the energy range where the "anomalous cosmic ray" fluxes of He, N, 0, and Ne have been observed. We compare the isotopic composition of the anomalous cosmic rays with that of higher-energy galactic cosmic rays in an eff...

The origin of the cosmic rays has been a great mystery since they were discovered by Victor Hess in 1912. AGASA’s observation of ultra-high-energy cosmic-rays (UHECR) possibly beyond the GZK (Greisen, Zatsepin and Kuzmin) cutoff stimulated the field in great deal. In addition, Kamiokande’s detection of neutrinos from SN1987A and the H.E.S.S.’s detection of TeV gamma-rays from supernova remnants...