Acceleration of relativistic protons in a CME-perturbed solar wind

Fuente: arXiv
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Autores principales: Houeibib, Ahmed, Pantellini, Filippo, Griton, Lea
Formato: Preprint
Publicado: 2026
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author Houeibib, Ahmed
Pantellini, Filippo
Griton, Lea
author_facet Houeibib, Ahmed
Pantellini, Filippo
Griton, Lea
contents We investigate the impact of a Coronal Mass Ejection (CME) on the transport and acceleration of relativistic protons in the solar wind using a coupled 3D Magnetohydrodynamics (MHD) simulation and a test-particle approach. The CME is driven by a spheromak injected into a Parker solar wind at a heliocentric distance of 0.139 AU. The trajectories of 5 GeV protons, injected towards the CME from 3 AU, are integrated in the guiding-centre approximation limit and scattered in velocity space with a mean free path $λ_{\|}$. Our results show that the CME can increment the protons energy by several GeV. The acceleration occurs during the time particles stream along the portion of a magnetic field line subject to compression downstream of the quasi-perpendicular portion of the CME-driven shock. In our configuration, the maximum energy gain, which is of the order of a few percent per shock crossing, occurs when the shock approaches 0.3 AU. Large energy gains require multiple passes through the acceleration region, which is made possible by the combined action of the mirror force and pitch angle scattering. The efficiency of the acceleration on time scales of the order of hours scales as $λ_{\|}^{-3/2}$. Energy spectra harden for decreasing parallel mean free path $λ_{\|}$.
format Preprint
id arxiv_https___arxiv_org_abs_2602_23723
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Acceleration of relativistic protons in a CME-perturbed solar wind
Houeibib, Ahmed
Pantellini, Filippo
Griton, Lea
Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
Space Physics
We investigate the impact of a Coronal Mass Ejection (CME) on the transport and acceleration of relativistic protons in the solar wind using a coupled 3D Magnetohydrodynamics (MHD) simulation and a test-particle approach. The CME is driven by a spheromak injected into a Parker solar wind at a heliocentric distance of 0.139 AU. The trajectories of 5 GeV protons, injected towards the CME from 3 AU, are integrated in the guiding-centre approximation limit and scattered in velocity space with a mean free path $λ_{\|}$. Our results show that the CME can increment the protons energy by several GeV. The acceleration occurs during the time particles stream along the portion of a magnetic field line subject to compression downstream of the quasi-perpendicular portion of the CME-driven shock. In our configuration, the maximum energy gain, which is of the order of a few percent per shock crossing, occurs when the shock approaches 0.3 AU. Large energy gains require multiple passes through the acceleration region, which is made possible by the combined action of the mirror force and pitch angle scattering. The efficiency of the acceleration on time scales of the order of hours scales as $λ_{\|}^{-3/2}$. Energy spectra harden for decreasing parallel mean free path $λ_{\|}$.
title Acceleration of relativistic protons in a CME-perturbed solar wind
topic Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
Space Physics
url https://arxiv.org/abs/2602.23723