Wave Emission and Absorption in a Near-Sun Proton-Cyclotron Wave Storm
Abstract
Quantification of energy transport and dissipation in weakly collisional heliospheric plasmas that are far from local thermodynamic equilibrium is an outstanding scientific problem. A central challenge is determining how non-Maxwellian velocity-space structure affects damping and emission of coherent ion-scale waves, especially compared to simplified analytical models for background plasma velocity distributions. In this work, we study the damping and emission of parallel-propagating proton cyclotron waves for two models of proton velocity distributions measured by the SPAN-I instrument on board Parker Solar Probe during an extended storm of waves with left-hand polarization in the solar wind at a heliocentric distance of 30.1 solar radii. Using the measured velocity distribution rather than a two-component bi-Maxwellian model predicts instabilities consistent with the observed coherent waves. For intervals in which both models predict net damping, the observed VDF model yields weaker damping in 90\% of cases, with a reduction in the integrated heating rate of 0.44 relative to the bi-Maxwellian model. These results suggest that simplified analytical velocity distribution models may overestimate cyclotron damping and underestimate wave emission in the near-Sun solar wind.
Related
- Perpendicular Heating of Solar Wind Protons Driven by Proton Cyclotron Waves Upstream of Mars
- Neutrino Emission from Proton Photon Jet Interactions in Microquasars
- Predicting High-Energy neutrino emission from X-ray absorption in CSM-interacting SNe
- XP-TEAL: Gaia XP Tool for Emission and Absorption Lines II. Gaia-HELIX catalogue of Hα emitters in Gaia BP/RP spectra
- Why is GN-z11 Bright, Compact, and Nitrogen Enhanced? Insights from UV Absorption and Emission Diagnostics
BibTeX
@misc{klein2026wave,
title = {{Wave Emission and Absorption in a Near-Sun Proton-Cyclotron Wave Storm}},
author = {Kristopher G Klein and Daniel Verscharen and Mihailo Martinovic and Niranjana and Ali Rahmati and Roberto Livi and Davin Larson and Michael Stevens},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10422},
eprint = {2609.10422},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10422},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Wave Emission and Absorption in a Near-Sun Proton-Cyclotron Wave Storm
AU - Kristopher G Klein
AU - Daniel Verscharen
AU - Mihailo Martinovic
AU - Niranjana
AU - Ali Rahmati
AU - Roberto Livi
AU - Davin Larson
AU - Michael Stevens
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.10422
UR - https://arxiv.org/abs/2609.10422
AB - Quantification of energy transport and dissipation in weakly collisional heliospheric plasmas that are far from local thermodynamic equilibrium is an outstanding scientific problem. A central challenge is determining how non-Maxwellian velocity-space structure affects damping and emission of coherent ion-scale waves, especially compared to simplified analytical models for background plasma velocity distributions. In this work, we study the damping and emission of parallel-propagating proton cyclotron waves for two models of proton velocity distributions measured by the SPAN-I instrument on board Parker Solar Probe during an extended storm of waves with left-hand polarization in the solar wind at a heliocentric distance of 30.1 solar radii. Using the measured velocity distribution rather than a two-component bi-Maxwellian model predicts instabilities consistent with the observed coherent waves. For intervals in which both models predict net damping, the observed VDF model yields weaker damping in 90\% of cases, with a reduction in the integrated heating rate of 0.44 relative to the bi-Maxwellian model. These results suggest that simplified analytical velocity distribution models may overestimate cyclotron damping and underestimate wave emission in the near-Sun solar wind.
ER -