cosmic rays in the upper troposphere (9000 meters to 15000 meters) initiate the followingnuclear chemical reaction: 1n + 14n => 14c + 1h. previous research has shown a strong effect of latitude onthe abundance of neutrons from cosmic rays. however, to date, there has been little exploration of therelationship between the latitude effect for cosmic-ray neutrons and latitudinal variations of stab...

It has been speculated that cosmic string networks could produce ultra-high energy cosmic rays as a by-product of their evolution. By making use of recent work on the evolution of such networks, it will be shown that the flux of cosmic rays from cosmologically useful, that is GUT scale strings, is too small to be used as a test for strings with any foreseeable technology.

In light of the mounting evidence that the highest energy cosmic rays are dominated by protons and not gammarays, we discuss the prospect that these cosmic rays are generated in the decay or annihilation of superheavy relic particles. We calculate the high energy neutrino spectrum which results and normalize our results to the ultrahigh energy cosmic ray spectrum. We show that most scenerios ar...

The recent HESS detections of supernova remnant shells in TeV γ-rays confirm the theoretical predictions that supernova remnants can operate as powerful cosmic ray accelerators. If these objects are responsible for the bulk of galactic cosmic rays, then they should accelerate protons and nuclei to 10eV and beyond, i.e. act as cosmic PeVatrons. The model of diffusive shock acceleration allows, u...

We predict a new class of intense, short-duration AGN flares resulting from the tidal disruption of a star or from a disk instability, and show that the rate and power of these flares can readily explain the observed flux and distribution of the highest energy cosmic rays. We describe the photon bursts produced by such AGN flares and show that they may soon be detectable. Subject headings: cosm...

Cosmic ray particles with energies in excess of 10 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 review of the physics and astrophysics associated with the questions of origin and propagation of these EHE cosmic rays in the Universe. After a brief review of the ob...

For our understanding of the origin of ultra high energy cosmic rays, the energy region between 10 17 and 10 19 eV is of crucial importance. Previous experiments have found indirect evidence that at these energies, the origin of cosmic rays changes from predominantly Galactic to extragalactic. In addition, weak evidence for an excess of cosmic rays from the direction of the Galactic center in a...

Gamma-Ray Bursts are good candidates of the “bottom up” scenario for the generation of the UHE Cosmic Rays. In the most discussed model of GRBs, namely the “fireball” model, a highly relativistic shock forms and seems capable of accelerating the cosmic rays up to the EeV range. However, only the first Fermi cycle produces a large energy gain to particles coming from the external medium. Thus, a...

We show that the luminosity of a star forming galaxy is capped by the production and subsequent expulsion of cosmic rays from its interstellar medium. By defining an Eddington luminosity in cosmic rays, we show that the star formation rate of a given galaxy is limited by its mass content and the cosmic ray mean free path. When the cosmic ray luminosity and pressure reaches a critical value as a...