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arXiv · 1010.0706

Two-Step Acceleration Model of Cosmic Rays at Middle-Aged SNR

Tsuyoshi Inoue·Ryo Yamazaki·Shu-ichiro Inutsuka
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Abstract

Recent gamma-ray observations of middle-aged supernova remnants revealed a mysterious broken power-law spectrum. Using three-dimensional magnetohydrodynamics simulations, we show that the interaction between a supernova blast wave and interstellar clouds formed by thermal instability generates multiple reflected shocks. The typical Mach numbers of the reflected shocks are shown to be M ~ 2 depending on the density contrast between the diffuse intercloud gas and clouds. These secondary shocks can further energize cosmic-ray particles originally accelerated at the blast-wave shock. This "two-step" acceleration scenario reproduces the observed gamma-ray spectrum and predicts the high-energy spectral index ranging approximately from 3 to 4.

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Tsuyoshi Inoue, Ryo Yamazaki, Shu-ichiro Inutsuka. 2010-10-04. Two-Step Acceleration Model of Cosmic Rays at Middle-Aged SNR. https://doi.org/10.1088/2041-8205%2F723%2F1%2Fl108

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