Origin of Cosmic Rays

Abstract

It is argued that there are three `origins' of cosmic rays; the origin of the particles, the origin of the energy, and the site of the acceleration. The evidence for each origin is discussed and a plausible synthesis outlined for the particles of Galactic origin where the energy comes mainly (but not exclusively) from supernova explosions, the site of the acceleration is at strong collisionless shock waves, and the accelerated particles come from the interstellar and circumstellar material swept over by these shocks. If these shocks are capable (as indicated by recent observations and theoretical work) of significantly amplifying magnetic fields this picture appears capable of explaining the cosmic ray particles at all energies below the `ankle' at $3\times 10^{18}\mathrm{eV}$. The particles above this energy are generally taken to be of extra-galactic origin and possible acceleration sites for these UHE particles are briefly discussed.

Review article to appear in special issue of Astroparticle Physics

References in corpus (13)

• The origin of the positron excess in cosmic rays
• Global cosmic-ray related luminosity and energy budget of the Milky Way
• Observations of the young supernova remnant RX J1713.7-3946 with the Fermi Large Area Telescope
• Measuring the cosmic ray acceleration efficiency of a supernova remnant
• Cosmological Shocks in Adaptive Mesh Refinement Simulations and the Acceleration of Cosmic Rays
• Diffusive Shock Acceleration with Magnetic Amplification by Non-resonant Streaming Instability in SNRs
• On Fermi acceleration and MHD-instabilities at ultra-relativistic magnetized shock waves
• Modeling the Multi-Wavelength Emission of Shell-Type Supernova Remnant RX J1713.7-3946
• Implications of the Cosmic Ray Electron Spectrum and Anisotropy measured with Fermi-LAT
• Magnetic Field Amplification and Rapid Time Variations in SNR RX J1713.7-3946
• Multiwavelength Signatures of Cosmic Ray Acceleration by Young Supernova Remnants
• Transition from Galactic to Extra-Galactic Cosmic Rays
• Radio Observations of Supernovae