On the possible reason for non-detection of TeV-protons in SNRs

Abstract

The theory of shock acceleration predicts the maximum particle energy to be limited only by the acceleration time and the size (geometry) of the shock. This led to optimistic estimates for the galactic cosmic ray energy achievable in the SNR shocks. The estimates imply that the accelerated particles, while making no strong impact on the shock structure (test particle approach) are nevertheless scattered by strong self-generated Alfven waves (turbulent boost) needed to accelerate them quickly. We demonstrate that these two assumptions are in conflict when applied to SNRs of the age required for cosmic ray acceleration to the ``knee'' energy. We study the combined effect of acceleration nonlinearity (shock modification by accelerated particles) and wave generation on the acceleration process. We show that the refraction of self-generated waves resulting from the deceleration of the plasma flow by the pressure of energetic particles causes enhanced losses of these particles. This effect slows down the acceleration and changes the shape of particle spectrum near the cut-off. The implications for observations of TeV emission from SNR remnants are also discussed.

26 pages, 4 figures, submitted to ApJ

References in corpus (5)

• Evidence for TeV gamma ray emission from Cassiopeia A
• X-Ray Synchrotron Emission from 10-100 TeV Cosmic-Ray Electrons in the Supernova Remnant SN 1006
• Accelerated Electrons in Cassiopeia A: An Explanation for the Hard X-ray Tail
• Shock Acceleration of Cosmic Rays - a critical review
• Modern theory of Fermi acceleration: a new challenge to plasma physics

Cited by in corpus (12)

• Limits on diffusive shock acceleration in supernova remnants in the presence of cosmic-ray streaming instability and wave dissipation
• Analytic Solution for Self-regulated Collective Escape of Cosmic Rays from their Acceleration Sites
• Nonlinear Diffusive Shock Acceleration with Magnetic Field Amplification
• Emission of SN 1006 produced by accelerated cosmic rays
• Direct Evidence for Hadronic Cosmic-Ray Acceleration in the Supernova Renmant IC 443
• Mechanism for spectral break in cosmic ray proton spectrum from Supernova remnant W44
• Hydrodynamic Simulation of Supernova Remnants Including Efficient Particle Acceleration
• Probing Nearby CR Accelerators and ISM Turbulence with Milagro Hot Spots
• Nonlinear shock acceleration beyond the Bohm limit
• Dynamics of Mesoscale Magnetic Field in Diffusive Shock Acceleration
• On the mechanism for breaks in the cosmic ray spectrum
• SNR G39.2-0.3, an Hadronic Cosmic Rays Accelerator