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Abstract We present a phenomenological and numerical study of strong Alfvénic turbulence in a magnetically dominated collisionless relativistic plasma with a strong background magnetic field. In contrast with the nonrelativistic case, the energy in such turbulence is contained in magnetic and electric fluctuations. We argue that such turbulence is analogous to turbulence in a strongly magnetized nonrelativistic plasma in the regime of broken quasi-neutrality. Our 2D particle-in-cell numerical simulations of turbulence in a relativistic pair plasma find that the spectrum of the total energy has the scaling k −3/2 , while the difference between the magnetic and electric energies, the so-called residual energy, has the scaling k −2.4 . The electric and magnetic fluctuations at scale ℓ exhibit dynamic alignment with the alignment angle scaling close to cos ϕ ℓ ∝ ℓ 1 / 4 . At scales smaller than the (relativistic) plasma inertial scale, the energy spectrum of relativistic inertial Alfvén turbulence steepens to k −3.5 .
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This content will become publicly available on May 15, 2027
Turbulence Mode Decomposition and Anisotropy in Magnetically Dominated Collisionless Plasmas
Abstract We use 3D fully kinetic simulations to study different turbulence modes and turbulence anisotropy of relativistic turbulence in magnetically dominated collisionless plasmas. We extend the method developed by J. Cho & A. Lazarian for decomposing nonrelativistic magnetohydrodynamic (MHD) turbulence into Alfvén, fast, and slow modes to the regime of collisionless plasmas. We find that Alfvén and slow modes are anisotropic, following the P. Goldreich & H. Sridhar scaling, while fast modes are isotropic. We observe a larger kinetic energy fraction of fast modes compared to that found in the nonrelativistic MHD turbulence, suggesting a stronger coupling of Alfvén and fast modes in relativistic magnetized turbulence in collisionless plasmas. We further examine the dynamic alignment and find a weaker scale dependence of the alignment angle than previously proposed. The dominant thermal fluctuations in the kinetic range can cause flattening of the turbulent velocity structure function and weakening of the turbulence anisotropy and dynamic alignment near the kinetic scales.
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- Award ID(s):
- 2308944
- PAR ID:
- 10692465
- Publisher / Repository:
- American Astronomical Society
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 1003
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 79
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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