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arXiv 2602.23723astro-ph.SRastro-ph.HEphysics.space-ph
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在CME扰动的太阳风中加速相对论性质子

Acceleration of relativistic protons in a solar wind perturbed by a coronal mass ejection

LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS(拉格朗日天体物理实验室,巴黎天文台,巴黎文理研究大学,索邦大学,巴黎西岱大学,塞吉-蓬图瓦兹大学,法国国家科学研究中心)

Ahmed Houeibib, Filippo Pantellini, Lea Griton

AI总结:

研究通过MHD模拟和测试粒子方法,探讨CME扰动下太阳风中相对论性质子的加速机制及能量增益过程。

摘要:

我们利用耦合的三维磁流体动力学(MHD)模拟和测试粒子方法,研究了日冕物质抛射(CME)对太阳风中相对论性质子的输运和加速的影响。CME由一个环形磁体注入到帕克太阳风中,距离太阳0.139个天文单位。5 GeV质子被注入到CME方向,从3个天文单位处开始,在引导中心近似极限下积分其轨迹,并在速度空间中与平均自由程λ∥散射。我们的结果表明,CME可以将质子的能量增加数GeV。加速发生在粒子沿磁力线压缩部分流经CME驱动激波的准垂直部分的时间内。在我们的配置中,最大能量增益,即每激波穿越几百分比,发生在激波接近0.3 AU时。大能量增益需要多次通过加速区域,这得益于镜力和pitch角散射的共同作用。在小时量级的时间尺度上,加速效率与λ∥的-3/2次方成比例。随着平行平均自由程λ∥的减小,能量谱变硬。

英文摘要:

We investigated 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. We integrated the trajectories of 5 GeV protons, injected toward the CME from 3 AU, in the guiding-center approximation and scattered the particles in velocity space with a mean free path $λ_{\|}$. Our results show that the CME can increase the protons' energy by several gigaelectronvolts. The acceleration occurs while particles stream along the portion of a magnetic field line downstream of the quasi-perpendicular portion of the CME-driven shock. In our configuration, the maximum energy gain, which is on the order of a few percent per passage through the acceleration region, occurs when the shock approaches 0.3 AU. Large energy gains require multiple passes through the acceleration region, made possible by the combined action of the mirror force and pitch-angle scattering. The efficiency of the acceleration on timescales on the order of hours scales as $λ_{\|}^{-3/2}$. Energy spectra harden with decreasing parallel mean free path $λ_{\|}$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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