Are E>B regions essential for particle injection in relativistic magnetic reconnection?
Abstract
During relativistic magnetic reconnection, X-points (E>B regions at vanishing guide field) have been proposed to play an essential role in injecting particles into the nonthermal population. Using fully kinetic particle-in-cell simulations at a range of magnetizations σ≡ B02/(4πn0 me c2) = 12--$800$, we study in detail how the particle energy gains up to the injection threshold γinj = σ/4 are partitioned into work done inside E>B regions (unmagnetized), within one gyration after exit (re-magnetizing), and at all other times (magnetized). The magnetized channel supplies the largest part of the energy gain for ∼ 95% of injected tracers at σ= 12 and ∼ 65% at σ= 800. Most of the tracers in this magnetized majority never enter an E>B region before injection. We also compare these injection shares with the earlier studies that proposed an essential role for E>B regions. We conclude that E>B regions are neither necessary for injection nor the dominant direct contributors to pre-injection work by injection share in two-dimensional, nonradiative pair-plasma reconnection at vanishing guide field.
Related
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BibTeX
@misc{french2026regions,
title = {{Are $E>B$ regions essential for particle injection in relativistic magnetic reconnection?}},
author = {Omar French and Fan Guo and Xiaocan Li and Qile Zhang and Yi-Hsin Liu and William Daughton and Hui Li},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.22118},
eprint = {2610.22118},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.22118},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Are E>B regions essential for particle injection in relativistic magnetic reconnection?
AU - Omar French
AU - Fan Guo
AU - Xiaocan Li
AU - Qile Zhang
AU - Yi-Hsin Liu
AU - William Daughton
AU - Hui Li
PY - 2026
DA - 2026/10/15
PB - arXiv
DO - 10.48550/arxiv.2610.22118
UR - https://arxiv.org/abs/2610.22118
AB - During relativistic magnetic reconnection, X-points (E>B regions at vanishing guide field) have been proposed to play an essential role in injecting particles into the nonthermal population. Using fully kinetic particle-in-cell simulations at a range of magnetizations σ≡ B_0^2/(4πn_0 m_e c^2) = 12--$800$, we study in detail how the particle energy gains up to the injection threshold γ_inj = σ/4 are partitioned into work done inside E>B regions (unmagnetized), within one gyration after exit (re-magnetizing), and at all other times (magnetized). The magnetized channel supplies the largest part of the energy gain for ∼ 95% of injected tracers at σ= 12 and ∼ 65% at σ= 800. Most of the tracers in this magnetized majority never enter an E>B region before injection. We also compare these injection shares with the earlier studies that proposed an essential role for E>B regions. We conclude that E>B regions are neither necessary for injection nor the dominant direct contributors to pre-injection work by injection share in two-dimensional, nonradiative pair-plasma reconnection at vanishing guide field.
ER -