113 research outputs found
Cosmic Ray Acceleration at the Galactic Wind Termination Shock with Self-Excited Alfven Waves
On the spectrum of high-energy cosmic rays produced by supernova remnants in the presence of strong cosmic-ray streaming instability and wave dissipation
The cosmic-ray streaming instability creates strong magnetohydrodynamic
turbulence in the precursor of a SN shock. The level of turbulence determines
the maximum energy of cosmic-ray particles accelerated by the diffusive shock
acceleration mechanism. The present consideration continues our work Ptuskin &
Zirakashvili (2003). It is assumed that the Kolmogorov type nonlinear wave
interactions together with the ion-neutral collisions restrict the amplitude of
random magnetic field. As a result, the maximum energy of accelerated particles
strongly depends on the age of a SNR. The average spectrum of cosmic rays
injected in the interstellar medium over the course of adiabatic SNR evolution
(the Sedov stage) is approximately at energies larger
than 10-30 Gev/nucleon and with the maximum particle energy that is close to
the knee position in cosmic ray spectrum observed at eV.
At earlier stage of SNR evolution - the ejecta dominated stage described by the
Chevalier-Nadyozhin solution, the particles are accelerated to higher energies
and have rather steep power-law distribution on momentum. These results suggest
that the knee may mark the transition from the ejecta-dominated to the
adiabatic evolution of SNR shocks which accelerate cosmic rays.Comment: 12 pages, 2 figures, LATE
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