نتایج جستجو برای: cosmic ray propagation
تعداد نتایج: 429239 فیلتر نتایج به سال:
The energy spectra of cosmic-ray protons and helium near solar minimum were precisely measured with BESS-Polar II (Balloon-borne Experiment with a Superconducting Spectrometer) during a long-duration flight over Antarctica in December 2007 and January 2008, and are discussed here. The absolute fluxes and spectral shapes of primary protons and helium probe the origin and the propagation history ...
The origin of ultra-high energy (UHE) cosmic rays is still an open question. In the present work, we searched the possible UHE cosmic ray sources using the MAGIC telescope for the associated very high energy (VHE) gamma ray emission. Due to constrained propagation distance of such cosmic rays, we selected nearby galaxies in vicinity of the direction of the AGASA triplet and a HiRes UHE cosmic r...
The individual energy spectra and relative abundances measured with TRACER, are compared with previous measurements in space and balloons, and with interpretations of air shower data. From the individual spectral slopes, we discuss constraints on models of cosmic-ray propagation through the galaxy. We also discuss the extrapolated high-energy abundances of the elements at the cosmic ray sources...
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...
Short Title: Cosmic-ray electrons and diffuse gamma-ray spectrum 1 Abstract The bulk of the diffuse galactic gamma-ray emission above a few tens of GeV has been conventionally ascribed to the decay of neutral pions produced in cosmic-ray interactions with interstellar matter. Cosmic-ray electrons may, however, make a significant contribution to the gamma-ray spectrum at high energies, and even ...
This paper summarizes highlights of the OG3.1, 3.2 and 3.3 sessions of the XXVIth International Cosmic Ray Conference in Salt Lake City, which were devoted to issues of origin/composition, acceleration and propagation.
It is presumed that the observed cosmic rays up to about 3 × 1018 eV are of Galactic origin, the particles being the ones which are found in the composition of the stellar winds of stars that explode as supernova into the interstellar medium (ISM) or into their winds. These particles are accelerated in the supernova shock. In order to obtain the observed cosmic ray spectrum it is necessary to t...
An overview is given on the present status of the understanding of the origin of galactic cosmic rays. Recent measurements of charged cosmic rays and photons are reviewed. Their impact on the contemporary knowledge about the sources and acceleration mechanisms of cosmic rays and their propagation through the Galaxy is discussed. Possible reasons for the knee in the energy spectrum and scenarios...
Confinement of cosmic rays by turbulent magnetic fields and the relation between magnetic and cosmic ray energy densities are investigated. Cosmic rays are assumed to diffuse preferentially along magnetic field lines. The implementation into a nonconservative high-order finite difference code is discussed. By solving an explicitly time-dependent equation for the cosmic ray energy flux, causalit...
An overview is given on the present status of the understanding of the origin of galactic cosmic rays. Recent measurements of charged cosmic rays and photons are reviewed. Their impact on the contemporary knowledge about the sources and acceleration mechanisms of cosmic rays and their propagation through the Galaxy is discussed. Possible reasons for the knee in the energy spectrum and scenarios...
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