Related papers: Gamma Ray Signatures from Ordinary Cosmic Strings
We study the spectrum of cosmic ray positrons produced by a scaling distribution of non-superconducting cosmic strings. In this scenario, the positrons are produced from the jets which form from the cosmic string cusp annihilation process.…
Ultra-high energy cosmic rays are the most extreme energetic particles detected on Earth, however, their acceleration sites are still mysterious. We explore the contribution of low-luminosity gamma-ray bursts to the ultra-high energy cosmic…
Gamma rays from TeV blazars have been detected by ground-based experiments for more than two decades. We have collected the most extensive set of archival spectra from these sources in order to constrain the processes affecting gamma-ray…
We present the results of OSSE observations of the soft gamma ray continuum emission from the Galactic plane at longitude 95 degrees. Emission is detected between 50 and 600 keV where the spectrum is fit well by a power law with photon…
Gamma-ray Astronomy studies cosmic accelerators through their electromagnetic radiation in the energy range between ~100 MeV and ~100 TeV. The present most sensitive observations in this energy band are performed, from space, by the Large…
One of the principal results obtained by the Compton Gamma Ray Observatory relating to the study of gamma-ray bursts was the detection by the EGRET instrument of energetic ($>$100 MeV) photons from a handful of bright bursts. The most…
We introduce neutrino astronomy from the observational fact that Nature accelerates protons and photons to energies in excess of 10^{20} and 10^{13} eV, respectively. Although the discovery of cosmic rays dates back close to a century, we…
The origin of Galactic cosmic rays (with energies up to 10^15 eV) remains unclear, though it is widely believed that they originate in the shock waves of expanding supernova remnants. Currently the best way to investigate their acceleration…
Cosmic strings can arise in hidden sector models with a spontaneously broken Abelian symmetry group. We have studied the couplings of the Standard Model fields to these so-called dark strings in the companion paper. Here we survey the…
Using the cosmic ray (CR) data available in the energy interval $(10 - 2 \times 10^{7})$ GeV/particle, we have calculated the profile of the primary $\gamma$-ray spectrum produced by the interaction of these CR with thermal nuclei of the…
I give a brief review of high energy gamma-ray signatures of dark matter. The decay of massive $X$-particles and subsequent hadronization have been suggested as the origin of the highest energy cosmic rays. Propagation over cosmological…
Investigations of the origin of cosmic rays are presented. Different methods are discussed: studies of cosmic gamma rays of energy from 30 MeV to about 10^15 eV (since photons point to their places of origin), studies of the mass…
The observed spatial distribution of $\gamma-$ray bursts indicates that they probably originate at cosmological distances. At this distance scale their variability timescale and flux above MeV imply an initial optical-depth to pair…
The propagation of very high energy gamma-rays ($E>100$~GeV) over cosmological distances is suppressed by pair-production processes with the ubiquitous extra-galactic soft photon background, mainly in the optical to near infra-red. The…
The distribution of cosmic rays in the Galaxy at energies above few TeVs is still uncertain and this affects the expectations for the diffuse gamma flux produced by hadronic interactions of cosmic rays with the interstellar gas. We show…
Many of the basic problems in the astrophysics of charged Cosmic Rays remain on principle unresolved by in situ observations in the Solar System due to the chaotic nature of the propagation of these particles in Interstellar space. This…
Gamma rays in the band from 30 MeV to 300 GeV, used in combination with direct measurements and with data from radio and X-ray bands, provide a powerful tool for studying the origin of Galactic cosmic rays. Gamma-ray Large Area Space…
Decaying topological defects, in particular cosmic strings, can produce a significant flux of high energy neutrinos, photons and cosmic rays. According to the prevailing understanding of cosmic string dynamics in an expanding Universe, the…
Physics beyond the standard model might imply the cosmological production of particles with grand unification scale energies. Nucleons and gamma-rays from such processes are candidates for the cosmic rays observed beyond 100 EeV [10**(20)…
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…