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


Using three-dimensional magnetohydrodynamics simulations, we show that the efficiency of cosmic-ray (CR) production at supernova remnants (SNRs) is over-predicted if it is 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 transfered into that of downstream turbulence as well as thermal energy which is related to the shock velocity component normal to the shock surface. In our case, the apparent efficiency goes up as high as $10\sim40\ \%$ in spite of no CR acceleration.

Read this paper on arXiv…

J. Shimoda, T. Inoue, Y. Ohira, et. al.
Wed, 10 Dec 14

Comments: 21 pages, 3 figures, 1 table, submitted to ApJ