Scale-Dependent Statistics of Coherent Magnetic Structures in Early IMAP Observations

Abstract

We analyze early Interstellar Mapping and Acceleration Probe (IMAP) magnetic field observations (November 2025 to May 2026) to quantify the statistical properties of helical magnetic structures and their relationship with turbulence intermittency. Intermittent structures, such as current sheets, are identified using the Partial Variance of Increments (PVI) method, and the scale-dependent normalized magnetic helicity is computed over scales corresponding to 0.5-3 correlation lengths. Prior studies have typically applied the PVI-helicity method to individual events; here we extend this technique to the ensemble statistics of a multi-month sample spanning many correlation times. To separate coherent helical structures from random turbulent fluctuations, significance thresholds for helicity are determined using phase-randomized surrogate realizations. We find a clear scale dependence in the occurrence, duration, and waiting time of coherent magnetic helicity, reminiscent of the scale-transfer arguments underlying inverse cascade, selective decay, and Taylor relaxation theories. Event duration and waiting-time distributions are well described by power-law and exponential models over different ranges, consistent with previous findings. In addition, PVI and magnetic helicity are anticorrelated, suggesting that high-PVI regions are preferentially associated with the boundaries of flux ropes, while their interiors tend to exhibit lower PVI and stronger magnetic helicity.

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BibTeX RIS

BibTeX

@misc{gautam2026scaledependent,
  title = {{Scale-Dependent Statistics of Coherent Magnetic Structures in Early IMAP Observations}},
  author = {Sujan Prasad Gautam and Francesco Pecora and Subash Adhikari and Riddhi Bandyopadhyay and Jiaming Wang and Joshua Goodwill and William Taranto and Rayta Pradata and William H. Matthaeus and David J. McComas and Eric Christian and Nathan Schwadron and Matina Gkioulidou and Jamie Rankin and Timothy S. Horbury and Savvas Raptis and Drew L. Turner},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.35634},
  eprint = {2610.35634},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.35634},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Scale-Dependent Statistics of Coherent Magnetic Structures in Early IMAP Observations
AU  - Sujan Prasad Gautam
AU  - Francesco Pecora
AU  - Subash Adhikari
AU  - Riddhi Bandyopadhyay
AU  - Jiaming Wang
AU  - Joshua Goodwill
AU  - William Taranto
AU  - Rayta Pradata
AU  - William H. Matthaeus
AU  - David J. McComas
AU  - Eric Christian
AU  - Nathan Schwadron
AU  - Matina Gkioulidou
AU  - Jamie Rankin
AU  - Timothy S. Horbury
AU  - Savvas Raptis
AU  - Drew L. Turner
PY  - 2026
DA  - 2026/10/26
PB  - arXiv
DO  - 10.48550/arxiv.2610.35634
UR  - https://arxiv.org/abs/2610.35634
AB  - We analyze early Interstellar Mapping and Acceleration Probe (IMAP) magnetic field observations (November 2025 to May 2026) to quantify the statistical properties of helical magnetic structures and their relationship with turbulence intermittency. Intermittent structures, such as current sheets, are identified using the Partial Variance of Increments (PVI) method, and the scale-dependent normalized magnetic helicity is computed over scales corresponding to 0.5-3 correlation lengths. Prior studies have typically applied the PVI-helicity method to individual events; here we extend this technique to the ensemble statistics of a multi-month sample spanning many correlation times. To separate coherent helical structures from random turbulent fluctuations, significance thresholds for helicity are determined using phase-randomized surrogate realizations. We find a clear scale dependence in the occurrence, duration, and waiting time of coherent magnetic helicity, reminiscent of the scale-transfer arguments underlying inverse cascade, selective decay, and Taylor relaxation theories. Event duration and waiting-time distributions are well described by power-law and exponential models over different ranges, consistent with previous findings. In addition, PVI and magnetic helicity are anticorrelated, suggesting that high-PVI regions are preferentially associated with the boundaries of flux ropes, while their interiors tend to exhibit lower PVI and stronger magnetic helicity.
ER  -

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