Spacetime Hall-MHD Turbulence at Sub-ion Scales: Structures or Waves?
Abstract
Spatiotemporal properties of two-dimensional (2D) Hall-magnetohydrodynamic (MHD) turbulence at intermediate plasma β = 2 are studied by means of Fast Iterative Filtering (FIF), a new technique for the decomposition of nonstationary nonlinear signals. Results show that the magnetic energy at sub-ion scales is concentrated in perturbations with frequencies smaller than the ion-cyclotron (IC) frequency and with polarization properties that are incompatible with both kinetic Alfvén waves (KAWs) and IC waves. At higher frequencies, we clearly identify signatures of both whistler waves and KAWs; however, their energetic contribution to the magnetic power spectrum is negligible. We conclude that the dynamics of 2D Hall-MHD turbulence at sub-ion scales is mainly driven by localized intermittent structures, with no significant contribution of wavelike fluctuations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2021
- DOI:
- 10.3847/2041-8213/ac11fd
- arXiv:
- arXiv:2107.03843
- Bibcode:
- 2021ApJ...917L..12P
- Keywords:
-
- Space plasmas;
- Solar wind;
- Interplanetary turbulence;
- Plasma astrophysics;
- 1544;
- 1534;
- 830;
- 1261;
- Physics - Plasma Physics;
- Physics - Space Physics
- E-Print:
- 10 pages, 5 figures. Accepted for publication on The Astrophysical Journal Letters