On cosmic-ray production efficiency at supernova remnant shocks propagating into realistic diffuse interstellar medium

Abstract

Using three-dimensional magnetohydrodynamics simulations, we show that the efficiency of cosmic-ray (CR) production at supernova remnants (SNRs) is over-predicted if it could be estimated based on proper motion measurements of H$\alpha$ filaments in combination with shock-jump conditions. Density fluctuations of upstream medium make shock waves rippled and oblique almost everywhere. The kinetic energy of the shock wave is transferred into that of downstream turbulence as well as thermal energy which is related to the shock velocity component normal to the shock surface. Our synthetic observation shows that the CR acceleration efficiency as estimated from a lower downstream plasma temperature, is overestimated by 10-40%, because rippled shock does not immediately dissipate all upstream kinetic energy.

7 pages, 3 figures, 1 table, accepted for publication in ApJ; the paper with full resolution images is http://www.phys.aoyama.ac.jp/~ryo/papers/shimoda2015.pdf

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• Polarized Balmer Line Emission from Supernova Remnant Shock Waves Efficiently Accelerating Cosmic Rays
• X-ray Line Diagnostics of Ion Temperature at Cosmic-Ray Accelerating Collisionless Shocks
• Radiative transfer of hydrogen lines from supernova remnant shock waves: contributions of 2s-state hydrogen atoms
• Cosmic-ray production from neutron escape in microquasar jets
• Measurement of the Forward Shock Velocities of the Supernova Remnant N132D Based on the Thermal X-ray Emission