Transport processes of high-energy cosmic rays in the interstellar medium

宇宙射线（CRs）是一种连续不断到达地球的高能粒子。主要成分（90%）由质子组成，其余为α粒子（<= 10%）、电子和较重的原子核。已知能量最高的CR粒子的加速机制在很大程度上仍然未知，部分原因是其来源尚未确定。与局部宇宙中agn的相关性仍然不确定，这也是因为这种高能粒子的数量密度很低。本项目的目的是研究高能CR粒子在星际介质（ISM）湍流电磁场中的散射。我们将评估从电子到铁核等不同质量粒子的输运过程。这将解决星系外CRs可能的偏转和各向同性问题，以及能量阈值（即Hillas极限），这是可能的。为此，将对ISM进行数值磁流体动力学（MHD）模拟。它们将为超新星引发的激波驱动的MHD湍流的演变提供洞见。cr的输运将采用两种不同的方法进行研究：(i)将测试粒子注入模拟立方体，并在磁化介质的演化过程中追踪它们的轨迹；（ii）基于MHD模拟的磁场相关参数进行蒙特卡罗模拟，并进行测试粒子代码。独立方法的组合将允许对调查中使用的假设进行批判性判断，因此将增加所获得的传输参数的可靠性。回答高能CRs起源的问题，不仅会让我们对已知的高能粒子的性质有更多的了解，而且还会帮助我们从总体上理解磁湍流。

Cosmic rays (CRs) are energetic particles that arrive on Earth in a continuous stream. The main component (90%) is represented by protons, with the rest being alpha particles (<= 10%), electrons, and heavier nuclei. The acceleration mechanisms of the CR particles with the highest energies known is still largely unknown, partly because the sources have not yet been identified. Correlations with AGNs in the local universe are still uncertain, also because of the low number density of such high-energy particles.It is the aim of this project to investigate the scattering of highest-energy CR particles in the turbulent electromagnetic fields of the interstellar medium (ISM). We will evaluate the transport processes of particles with various masses, ranging from electrons to iron nuclei. This will address the problem of a possible deflection and isotropization of extra-galactic CRs and the energy threshold (i.e., the Hillas limit) up to which this is possible.For this purpose numerical magneto-hydrodynamical (MHD) simulations of the ISM will be performed. They will provide insight into the evolution of MHD turbulence driven by supernova-induced shock waves. The transport of CRs will be investigated using two different approaches: (i) test-particles will be injected into the simulation cube and their trajectories are traced during the evolution of the magnetized medium; (ii) based on magnetic field correlation parameters from the MHD simulation Monte-Carlo simulations with a test-particle code will be carried out.The combination of independent methods will allow for a critical judgment of the assumptions used in the investigations and will therefore increase the reliability of the obtained transport parameters. Answering the questions of the origin of high-energy CRs will not only allow for an increased understanding of the nature of the most energetic particles known, but will also help the understanding of magnetic turbulence in general.