Comment on "Nonideal Fields Solve the Injection Problem in Relativistic Reconnection"

Abstract

Recently, Sironi (PRL, 128, 145102; S22) reported the correlation between particles accelerated into high energy and their crossings of regions with electric field larger than magnetic field (E>B regions) in kinetic simulations of relativistic magnetic reconnection. They claim that electric fields in E>B regions (for a vanishing guide field) dominate in accelerating particles to the injection energy. S22 presented test-particle simulations showing that if particle energies are reset to low energies in E>B regions, efficient injection is suppressed. This Comment re-examines these claims by analyzing a simulation resembling the reference case in S22. We show that during crossings E>B acceleration only contributes a small fraction to the injection energy as E>B regions only host particles for a short duration. The energization before any E>B crossings has a comparable contribution, indicating E>B regions are not unique in pre-accelerating particles. A new test-particle simulation shows that zero-outing electric fields in E>B regions does not strongly influence the injection. We suggest that the procedure used in S22 to exclude E>B acceleration partly removes acceleration outside E>B regions, leading to a false conclusion.

2 pages, 1 figure

References in corpus (7)

• Formation of Hard Power-laws in the Energetic Particle Spectra Resulting from Relativistic Magnetic Reconnection
• Why does steady-state magnetic reconnection have a maximum local rate of order 0.1?
• Scaling of magnetic reconnection in relativistic collisionless plasmas
• Recent Progress on Particle Acceleration and Reconnection Physics during Magnetic Reconnectionin the Magnetically-dominated Relativistic Regime
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• Non-ideal fields solve the injection problem in relativistic reconnection

Cited by in corpus (6)

• A Model for Nonthermal Particle Acceleration in Relativistic Magnetic Reconnection
• Particle acceleration by magnetic reconnection in relativistic jets: the transition from small to large scales
• Exact Calculation of Nonideal Fields Demonstrates Dominance of Injection in Relativistic Reconnection
• Leaking Outside the Box: Kinetic Turbulence with Cosmic-Ray Escape
• Low-energy Injection and Nonthermal Particle Acceleration in Relativistic Magnetic Turbulence
• Particle injection in three-dimensional relativistic magnetic reconnection