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arXiv 2011.02238astro-ph.HEphysics.plasm-ph
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宇宙射线对源周围介质的动力学效应

Dynamical Effects of Cosmic Rays on the Medium Surrounding Their Sources

Benedikt Schroer, Oreste Pezzi, Damiano Caprioli, Colby Haggerty, Pasquale Blasi

摘要:

宇宙射线(CR)主要沿着局部磁场离开它们的源;在这样做的过程中,它们通过流动不稳定性激发共振和非共振模式。这些模式的激发导致增强的散射,进而导致大的压力梯度,导致形成气泡的气体,CR和自生磁场扩展到星际介质。通过混合粒子在细胞模拟,我们表明,通过激发非共振不稳定性,CR挖掘其源周围的扩散率被强烈抑制的空腔。这一发现使迄今为止广泛采用的磁通管假设无效,在磁通管假设下,即使在非线性状态下,粒子也沿着磁力线运动。这种现象是普遍的,预计会发生在银河系中任何足够强大的CR源周围。我们的研究结果可能会提供一个物理解释的抑制CR扩散周围的星系源,如超新星遗迹,脉冲星风星云,和星团的众多索赔。

英文摘要:

Cosmic rays (CRs) leave their sources mainly along the local magnetic field; in doing so they excite both resonant and nonresonant modes through streaming instabilities. The excitation of these modes leads to enhanced scattering and in turn to a large pressure gradient that causes the formation of bubbles of gas, CRs, and self-generated magnetic fields expanding into the interstellar medium. By means of hybrid Particle-In-Cell simulations, we show that, by exciting the nonresonant instability, CRs excavate a cavity around their source where the diffusivity is strongly suppressed. This finding invalidates the so far largely adopted flux-tube assumption, under which particles move along magnetic lines even in the nonlinear regime. This phenomenon is general and is expected to occur around any sufficiently powerful CR source in the Galaxy. Our results might provide a physical explanation of the numerous claims of suppressed CR diffusion around Galactic sources such as supernova remnants, pulsar wind nebulae, and stellar clusters.

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