Gamma Rays from Ultra-High-Energy Cosmic Rays in Cygnus A
نویسندگان
چکیده
منابع مشابه
3 Se p 20 08 Gamma Rays from Ultra - High Energy Cosmic Rays in Cygnus A
Ultra-high energy cosmic rays (UHECRs) accelerated in the jets of active galactic nuclei can accumulate in high magnetic field, ∼ 100 kpc-scale regions surrounding powerful radio galaxies. Photohadronic processes involving UHECRs and photons of the extragalactic background light make ultra-relativistic electrons and positrons that initiate electromagnetic cascades, leading to the production of ...
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Gamma-ray bursts (GRBs) are sources of energetic, highly variable fluxes of γ rays, which demonstrates that they are powerful particle accelerators. Besides relativistic electrons, GRBs should also accelerate high-energy hadrons, some of which could escape cooling to produce ultra-high energy cosmic rays (UHECRs). Acceleration of high-energy hadrons in GRB blast waves will be established if hig...
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The current status of Ultra High Energy Cosmic Rays (UHECR) is reviewed, with emphasis given to theoretical interpretation of the observed events. The galactic and extragalactic origin, in case of astrophysical sources of UHE particles, have the problems either with acceleration to the observed energies or with the fluxes and spectra. Topological defects can naturally produce particles with ene...
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The origin of the particles in the highest energy end of the cosmic ray spectrum is discussed in the context of the wider problem of the origin of the whole cosmic radiation as observed at the Earth. In particular we focus our attention on the acceleration problem and on the transition from galactic to extragalactic cosmic rays.
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We discuss theoretical issues and experimental data that brought the ultra high energy cosmic rays in the list of Nature’s greatest puzzles. After many years of research we still do not know how astrophysical acceleration processes can reach energies exceeding 10 GeV. The main alternative top-down mechanism postulates the existence of super massive X-particles that create a particle spectrum ex...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2008
ISSN: 0004-637X,1538-4357
DOI: 10.1086/593202