Related papers: Origin(s) of Cosmic Rays
Recent studies, supported by updated hadronic interaction models, suggest that the mass composition of ultra-high-energy cosmic rays may be heavier than previously assumed. This has significant implications for source identification, as the…
The origin of the highest energy cosmic rays represents one of the most conspicuous enigmas of modern astrophysics, in spite of gigantic experimental efforts in the past fifty years, and of active theoretical research. The past decade has…
Ultrarelativistic particles called cosmic rays permeate the Milky Way, propagating through the Galactic turbulent magnetic fields. The mechanisms under which these particles increase their energy can be reasonably described by current…
Cosmic-rays with energies exceeding 10^{19} eV are referred to as Ultra High Energy Cosmic Rays (UHECRs). The sources of these particles and their acceleration mechanism are unknown, and for many years have been the issue of much debate.…
The paper presents the nowdays definition of the phenomenon of cosmic gamma ray bursts, refers to the main alternative models of their origin and proposes three promising domains of new observations in the incoming decade.
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…
Most cosmic rays are thought to be accelerated by the shocks of supernova explosions of very massive stars. Here we review one quantitative proposal, which predicted the spectral slopes, bend and cutoff about the cosmic ray spectrum across…
Astrophysical sources are extremely efficient accelerators. Some sources emit photons up to multi-TeV energies, a signature of the presence, within them, of particles with energies much higher than those achievable with the largest…
An extragalactic origin of the dominant part of all extrasolar hadronic cosmic rays above about 10 MeV/nucleon has long been considered unlikely due to energy considerations. In order to circumvent such arguments, the hypothesis that ``flux…
The physics of energetic particle propagation in magnetised environments plays a crucial role in both the processes of acceleration and transport of cosmic rays. Recent theoretical developments in the field of cosmic ray research have been…
Continuum gamma-ray emission produced by interactions of cosmic rays with interstellar matter and radiation fields is a probe of non-thermal particle populations in galaxies. After decades of continuous improvements in experimental…
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 $\Delta$…
Cosmic rays at the Earth include a secondary component originating in collisions of primary particles with the diffuse interstellar gas. The secondary cosmic rays are relatively rare but carry important information on the Galactic…
A review of the status of the knowledge in the field of High-energy cosmic particles is presented. The spectrum, arrival direction distribution and composition measurements are summarized, together with some implications for the…
I give a synopsis of two aspects of the Galactic Cosmic Ray (GCR) acceleration problem: the importance of the medium energy gamma-ray window, and several specific astrophysical sources which merit further investigation.
We shortly discuss several astrophysical scenarios leading to cosmic ray acceleration up to extremely high energies reaching the scale of 10^{20} eV. The processes suggested in the literature include acceleration at relativistic jet…
Be abundances at low metallicities have major implications on cosmic ray origin, requiring acceleration out of fresh supernova ejecta. The observed, essentially constant Be/Fe fixes the Be production per SNII, allowing the determination of…
We review recent progress in our understanding of the physics of energetic particles in our Galaxy, in active galaxies such as starburst galaxies, in active galactic nuclei and in the jets and radio hot spots of powerful radio galaxies and…
The latest results from PAMELA and FERMI experiments confirm the necessity to improve theoretical models of production and propagation of galactic electrons and positrons. There are many possible explanations for the positron excess…
Although Galactic cosmic rays (protons and nuclei) are widely believed to be dominantly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery [1].…