标题： 银河系超新星遗迹周围的宇宙线质量和数量 显示英文标题

标题： Grammage of cosmic rays around Galactic supernova remnants

摘要： 宇宙射线（CRs）在银河系中的逗留时间通常通过次级核与初级核的比例测量来推断，例如硼（B）/碳（C）的比例，它提供了CRs在传播过程中穿过的物质量的估计值，即所谓的CR“grammage”。 然而，在由其母源（例如超新星遗迹SNRs）释放后，CRs必须穿越银河盘面，然后进入密度低得多的晕，人们认为它们在那里度过了大部分时间，直到最终逃离银河系。 在源附近区域，研究表明CR传播受波的非线性自生成效应主导。 我们展示出由于这一效应，能量高达 $\sim$ 10 TeV 的CRs 在距离源 $L_{c}\sim 100$ pc 范围内停留的时间比简单估算所建议的要长得多。 相应的grammage接近当前对整个银河系中总grammage的估计值。 此外，存在一个不可减少的grammage，CRs在被加速它们的冲击波下游捕获时穿过该区域，尽管这一贡献相当不确定。 我们得出结论，在能量 $\lesssim 1$ TeV 时，观测到的grammage受到源附近的非线性捕获的强烈影响，在能量 $\gtrsim 1$ TeV 时则受到源grammage的影响。 因此，应谨慎使用B/C比例作为衡量CRs在银河系大尺度传播的指标。 显示英文摘要

摘要： The residence time of cosmic rays (CRs) in the Galaxy is usually inferred from the measurement of the ratio of secondary-to-primary nuclei, such as the boron (B)/carbon (C) ratio, which provides an estimate of the amount of matter traversed by CRs during their propagation, the so called CR grammage. However, after being released by their parent sources, for instance supernova remnants (SNRs), CRs must cross the disc of the Galaxy, before entering the much lower density halo, in which they are believed to spend most of the time before eventually escaping the Galaxy. In the near-source region, the CR propagation is shown to be dominated by the non-linear self-generation of waves. Here we show that due to this effect, the time that CRs with energies up to $\sim$ 10 TeV spend within a distance $L_{c}\sim 100$ pc from the sources is much larger than naive estimates would suggest. The corresponding grammage is close to current estimates of the total grammage traversed throughout the whole Galaxy. Moreover, there is an irreducible grammage that CRs traverse while trapped downstream of the shock that accelerated them, though this contribution is rather uncertain. We conclude that at energies $\lesssim 1$ TeV, the observed grammage is heavily affected by the near-source non-linear trapping of CRs, and at energies $\gtrsim 1$ TeV it is affected by the source grammage. As a result, the measurement of the B/C ratio should be used very cautiously as an indicator of the propagation of CRs on large Galactic scales.