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Title: COMPRESSIBLE RELATIVISTIC MAGNETOHYDRODYNAMIC TURBULENCE IN MAGNETICALLY DOMINATED PLASMAS AND IMPLICATIONS FOR A STRONG-COUPLING REGIME

Abstract

In this Letter, we report compressible mode effects on relativistic magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using three-dimensional numerical simulations. We decomposed fluctuations in the turbulence into 3 MHD modes (fast, slow, and Alfvén) following the procedure of mode decomposition in Cho and Lazarian, and analyzed their energy spectra and structure functions separately. We also analyzed the ratio of compressible mode to Alfvén mode energy with respect to its Mach number. We found the ratio of compressible mode increases not only with the Alfvén Mach number, but also with the background magnetization, which indicates a strong coupling between the fast and Alfvén modes. It also signifies the appearance of a new regime of RMHD turbulence in Poynting-dominated plasmas where the fast and Alfvén modes are strongly coupled and, unlike the non-relativistic MHD regime, cannot be treated separately. This finding will affect particle acceleration efficiency obtained by assuming Alfvénic critical-balance turbulence and can change the resulting photon spectra emitted by non-thermal electrons.

Authors:
 [1];  [2]
  1. Department of Earth and Planetary Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan)
  2. Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States)
Publication Date:
OSTI Identifier:
22654168
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 831; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ALFVEN WAVES; COMPUTERIZED SIMULATION; EFFICIENCY; ELECTRONS; EMISSION; ENERGY SPECTRA; FLUCTUATIONS; MACH NUMBER; MAGNETIC FIELDS; MAGNETIZATION; MAGNETOHYDRODYNAMICS; PHOTONS; PLASMA; RELATIVISTIC RANGE; STRONG-COUPLING MODEL; STRUCTURE FUNCTIONS; THREE-DIMENSIONAL CALCULATIONS; TURBULENCE

Citation Formats

Takamoto, Makoto, and Lazarian, Alexandre. COMPRESSIBLE RELATIVISTIC MAGNETOHYDRODYNAMIC TURBULENCE IN MAGNETICALLY DOMINATED PLASMAS AND IMPLICATIONS FOR A STRONG-COUPLING REGIME. United States: N. p., 2016. Web. doi:10.3847/2041-8205/831/2/L11.
Takamoto, Makoto, & Lazarian, Alexandre. COMPRESSIBLE RELATIVISTIC MAGNETOHYDRODYNAMIC TURBULENCE IN MAGNETICALLY DOMINATED PLASMAS AND IMPLICATIONS FOR A STRONG-COUPLING REGIME. United States. https://doi.org/10.3847/2041-8205/831/2/L11
Takamoto, Makoto, and Lazarian, Alexandre. Thu . "COMPRESSIBLE RELATIVISTIC MAGNETOHYDRODYNAMIC TURBULENCE IN MAGNETICALLY DOMINATED PLASMAS AND IMPLICATIONS FOR A STRONG-COUPLING REGIME". United States. https://doi.org/10.3847/2041-8205/831/2/L11.
@article{osti_22654168,
title = {COMPRESSIBLE RELATIVISTIC MAGNETOHYDRODYNAMIC TURBULENCE IN MAGNETICALLY DOMINATED PLASMAS AND IMPLICATIONS FOR A STRONG-COUPLING REGIME},
author = {Takamoto, Makoto and Lazarian, Alexandre},
abstractNote = {In this Letter, we report compressible mode effects on relativistic magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using three-dimensional numerical simulations. We decomposed fluctuations in the turbulence into 3 MHD modes (fast, slow, and Alfvén) following the procedure of mode decomposition in Cho and Lazarian, and analyzed their energy spectra and structure functions separately. We also analyzed the ratio of compressible mode to Alfvén mode energy with respect to its Mach number. We found the ratio of compressible mode increases not only with the Alfvén Mach number, but also with the background magnetization, which indicates a strong coupling between the fast and Alfvén modes. It also signifies the appearance of a new regime of RMHD turbulence in Poynting-dominated plasmas where the fast and Alfvén modes are strongly coupled and, unlike the non-relativistic MHD regime, cannot be treated separately. This finding will affect particle acceleration efficiency obtained by assuming Alfvénic critical-balance turbulence and can change the resulting photon spectra emitted by non-thermal electrons.},
doi = {10.3847/2041-8205/831/2/L11},
url = {https://www.osti.gov/biblio/22654168}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 831,
place = {United States},
year = {2016},
month = {11}
}