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

高能宇宙线在星际介质中的传输过程

• 批准号: 263050076
• 负责人: Professor Dr. Dieter Breitschwerdt
• 金额: --
• 依托单位: Zentrum für Astronomie und Astrophysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/263050076?language=en
• 关键词: Transport; processes; energy; cosmic; rays

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.

宇宙射线（CR）是以连续流到达地球的高能粒子。主要成分（90%）是质子，其余是α粒子（<= 10%），电子和更重的原子核。已知能量最高的CR粒子的加速机制在很大程度上仍然是未知的，部分原因是来源尚未确定。由于这些高能粒子的数量密度很低，因此它们与活动星系核的相关性仍然不确定。本项目的目的是研究最高能量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的各种质量的粒子的输运过程。这将解决银河系外CRs可能偏转和各向同性的问题以及能量阈值（即，希拉斯极限），这是可能的。为此，数值磁流体动力学（MHD）模拟的ISM将进行。他们将提供深入了解由超新星引起的冲击波驱动的MHD湍流的演变。将采用两种不同的方法研究CRs的输运：（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跟踪它们的轨迹;（ii）根据磁流体动力学模拟蒙特-卡罗模拟的磁场相关参数，并进行试验-粒子代码将进行。独立的方法的组合将允许在调查中使用的假设的关键判断，因此将增加的可靠性获得了运输参数。解决高能CRs的起源问题不仅可以增加对已知最高能粒子性质的理解，而且还有助于理解一般的磁湍流。