Studying the mirror acceleration via kinetic simulations of relativistic plasma turbulence

Fuente: arXiv
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Autori principali: Das, Saikat, Xu, Siyao, Nättilä, Joonas
Natura: Preprint
Pubblicazione: 2025
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author Das, Saikat
Xu, Siyao
Nättilä, Joonas
author_facet Das, Saikat
Xu, Siyao
Nättilä, Joonas
contents Efficient relativistic turbulent acceleration of particles is indicated by recent astrophysical observations. The Type II mechanism with acceleration due to the temporal variations of magnetic field strengths remains underexplored. The mirror acceleration has recently been proposed as an efficient Type II mechanism for particle energization in turbulence-compressed magnetic fields. We perform a 3D particle-in-cell (PIC) simulation of pair plasma to extend its study to relativistic turbulence. By tracking individual particles, we see that the particles interacting with transverse magnetic mirrors can have a significant energy gain during one mirror interaction and within one gyro-orbit. As expected for the mirror acceleration, we statistically find that the momentum gain is preferentially in the direction perpendicular to the local magnetic field and positively correlated with the local magnetic field strengthening. As a result, the particle pitch angle distribution becomes increasingly anisotropic toward higher energies, with a concentration at large pitch angles. The mirror acceleration facilitates a spatial confinement of particles by stochastically increasing their pitch angles, which further enhances the mirror acceleration.
format Preprint
id arxiv_https___arxiv_org_abs_2506_04212
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Studying the mirror acceleration via kinetic simulations of relativistic plasma turbulence
Das, Saikat
Xu, Siyao
Nättilä, Joonas
High Energy Astrophysical Phenomena
Plasma Physics
Efficient relativistic turbulent acceleration of particles is indicated by recent astrophysical observations. The Type II mechanism with acceleration due to the temporal variations of magnetic field strengths remains underexplored. The mirror acceleration has recently been proposed as an efficient Type II mechanism for particle energization in turbulence-compressed magnetic fields. We perform a 3D particle-in-cell (PIC) simulation of pair plasma to extend its study to relativistic turbulence. By tracking individual particles, we see that the particles interacting with transverse magnetic mirrors can have a significant energy gain during one mirror interaction and within one gyro-orbit. As expected for the mirror acceleration, we statistically find that the momentum gain is preferentially in the direction perpendicular to the local magnetic field and positively correlated with the local magnetic field strengthening. As a result, the particle pitch angle distribution becomes increasingly anisotropic toward higher energies, with a concentration at large pitch angles. The mirror acceleration facilitates a spatial confinement of particles by stochastically increasing their pitch angles, which further enhances the mirror acceleration.
title Studying the mirror acceleration via kinetic simulations of relativistic plasma turbulence
topic High Energy Astrophysical Phenomena
Plasma Physics
url https://arxiv.org/abs/2506.04212