We describe the results of a hybrid matrix{Monte Carlo calculation of cascading of UHE cosmic rays and-rays through the cosmic background radiation elds over cosmological distances. We calculate the-ray and neutrino emission that results from the cascade, as well as the eeect of cascading on the primary spectrum. We discuss the results for various cosmic ray injection spectra and primary specie...

The investigation of very high energy cosmic rays and their interactions are inherently connected subjects of astroparticle physics. On one hand the understanding of cosmic ray interactions is needed to study the flux, acceleration and propagation of cosmic rays. For example, the high energy cosmic ray flux can only be measured by linking secondary particle cascades observed in detectors or the...

Galactic cosmic rays have been positively correlated to the Earth’s low cloud cover. It is now evident that cosmic ray ionization is linked to lowering nucleation barriers and promoting early charged particle growth into the Aitken range. There is a substantially high probability that some of the charged particles grow to the 100 nm range and beyond to become CCN. There is also evidence that el...

Star formation and supermassive black hole growth in galaxies appear to be self-limiting. The mechanisms for self-regulation are known as feedback. Cosmic rays, the relativistic particle component of interstellar and intergalactic plasma, are among the agents of feedback. Because cosmic rays are virtually collisionless in the plasma environments of interest, their interaction with the ambient m...

— Cosmic rays physics is currently being studied with rather sophisticated detectors running in a variety of experimental conditions and atmospheric depths around the world. In this paper we describe the reasons why cosmic ray physics experiments at high altitudes like Chacaltaya are so important for resolving some of the open problems in cosmic physics. A discussion on the future prospects of ...

Clusters of galaxies have not yet been detected at gamma-ray frequencies; however, the recently launched Fermi Gamma-ray Space Telescope, formerly known as GLAST, could provide the first detections in the near future. Clusters are expected to emit gamma rays as a result of (1) a population of high-energy cosmic rays fueled by accretion, merger shocks, active galactic nuclei and supernovae, and ...

Particle acceleration at supernova remnant (SNR) shock waves is regarded as the most probable mechanism for providing Galactic cosmic rays at energies below 10 eV. The Galactic cosmic ray hadron component would in this picture result from the injection of relativistic particles from many SNRs. It is well known that the superposition of individual power law source spectra with dispersion in the ...

Astrophysical bounds on the properties and abundances of primordial quark nuggets and cosmic ray strangelets are reviewed. New experiments to search for cosmic ray strangelets in lunar soil and from the International Space Station are described. Analogies with baryonic and supersymmetric Q-balls are briefly mentioned, as are prospects for strangelets as ultra-high energy cosmic rays.

We suggest that the highest energy > ∼ 10eV cosmic ray primaries may be relativistic magnetic monopoles. Motivations for this hypothesis are that conventional primaries are problematic, while monopoles are naturally accelerated to E ∼ 10eV by galactic magnetic fields. By matching the cosmic monopole production mechanism to the observed highest energy cosmic ray flux we estimate the monopole mas...