http://arxiv.org/abs/1609.04851
We present results from particle-in-cell simulations of driven turbulence in collisionless, relativistic pair plasma. We find that turbulent fluctuations are consistent with the classical $k_\perp^{-5/3}$ magnetic energy spectrum at fluid scales and a steeper $k_\perp^{-4}$ spectrum at sub-Larmor scales, where $k_\perp$ is the wavevector perpendicular to the mean field. We demonstrate the development of a non-thermal, power-law particle energy distribution, $f(E) \sim E^{-\alpha}$, with index well fit by $\alpha \sim 1 + C_0 (\sigma \rho_e/L)^{-1/2}$, where $C_0$ is a constant, $\sigma$ is magnetization, and $\rho_e/L$ is the ratio of characteristic Larmor radius to system size. In the absence of asymptotic system-size independent scalings, our results challenge the viability of turbulent particle acceleration in high-energy astrophysical systems such as pulsar wind nebulae.
V. Zhdankin, G. Werner, D. Uzdensky, et. al.
Mon, 19 Sep 16
13/52
Comments: 6 pages, 4 figures, submitted to PRL
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