Numerical investigation of kinetic turbulence in relativistic pair plasmas \textendash I. Turbulence statistics

Author
Abstract
<p>We describe results from particle-in-cell simulations of driven turbulence in collisionless, magnetized, relativistic pair plasma. This physical regime provides a simple setting for investigating the basic properties of kinetic turbulence and is relevant for high-energy astrophysical systems such as pulsar wind nebulae and astrophysical jets. In this paper, we investigate the statistics of turbulent fluctuations in simulations on lattices of up to 1024<sup>3</sup>\&nbsp;cells and containing up to 2\&nbsp;\texttimes\&nbsp;10<sup>11</sup>\&nbsp;particles. Due to the absence of a cooling mechanism in our simulations, turbulent energy dissipation reduces the magnetization parameter to order unity within a few dynamical times, causing turbulent motions to become sub-relativistic. In the developed stage, our results agree with predictions from magnetohydrodynamic turbulence phenomenology at inertial-range scales, including a power-law magnetic energy spectrum with index near -5/3, scale-dependent anisotropy of fluctuations described by critical balance, lognormal distributions for particle density and internal energy density (related by a 4/3 adiabatic index, as predicted for an ultra-relativistic ideal gas), and the presence of intermittency. We also present possible signatures of a kinetic cascade by measuring power-law spectra for the magnetic, electric and density fluctuations at sub-Larmor scales.</p>
Year of Publication
2017
Journal
Monthly Notices of the Royal Astronomical Society
Volume
474
Start Page
2514
Number of Pages
2514-2535
Date Published
2017-11
ISSN Number
0035-8711
URL
https://academic.oup.com/mnras/article/474/2/2514/4600561
DOI
10.1093/mnras/stx2883
JILA PI
Journal Article