PreprintCC BY 4.0arXiv
Equipartition between Alfvénic turbulence and energetic ions as the origin of the -5 common spectrum in the heliosphere
Abstract
Suprathermal ion tails throughout the heliosphere follow a ``common spectrum,'' f(v)∝ v−5. We show that scale-by-scale equipartition between strong Alfvénic turbulence and the ions it accelerates predicts both this exponent and the absolute amplitude, F(v)=B2/(16π3 mi v5), with no free parameters. The prediction agrees within a factor of a few with ACE and Voyager 1 spectra across three decades in magnetic energy. We argue that this saturated level is reached where strong turbulence accelerates particles locally; quiet-time tails lie well below it, consistent with nonlocal acceleration.
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BibTeX
@misc{boldyrev2026equipartition,
title = {{Equipartition between Alfvénic turbulence and energetic ions as the origin of the -5 common spectrum in the heliosphere}},
author = {Stanislav Boldyrev and Daniel Humphrey and Vadim Roytershteyn},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40925},
eprint = {2610.40925},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40925},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Equipartition between Alfvénic turbulence and energetic ions as the origin of the -5 common spectrum in the heliosphere
AU - Stanislav Boldyrev
AU - Daniel Humphrey
AU - Vadim Roytershteyn
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40925
UR - https://arxiv.org/abs/2610.40925
AB - Suprathermal ion tails throughout the heliosphere follow a ``common spectrum,'' f(v)∝ v^−5. We show that scale-by-scale equipartition between strong Alfvénic turbulence and the ions it accelerates predicts both this exponent and the absolute amplitude, F(v)=B^2/(16π^3 m_i v^5), with no free parameters. The prediction agrees within a factor of a few with ACE and Voyager 1 spectra across three decades in magnetic energy. We argue that this saturated level is reached where strong turbulence accelerates particles locally; quiet-time tails lie well below it, consistent with nonlocal acceleration.
ER -