The impact of cosmic rays on the multi-phase structure of the turbulent interstellar medium

宇宙射线对湍流星际介质多相结构的影响

• 批准号: 263067211
• 负责人: Dr. Thorsten Naab
• 金额: --
• 依托单位: Max-Planck-Institut für Astrophysik (MPA)
• 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/263067211?language=en
• 关键词: impact; cosmic; rays; multi; phase

Cosmic rays (CR) are an integral (non-thermal) part of the interstellar medium (ISM). They are most likely accelerated in strong shocks generated by supernova explosions and propagate into the ISM along magnetic field lines. Due to the low energy loss rates they can be transported over large distances and can be a significant energy and momentum source for the thermal ISM gas (provided they can couple), also in regions of low density. Analytical and one-dimensional calculations have indicated a significant impact of CRs on the ISM properties with the potential of driving large scale outflows. This was indicated by approximate galaxy scale simulations. However, no detailed magneto-hydrodynamical (MHD) simulations of the dynamical impact of CRs on the turbulent ISM have been performed so far. We propose to perform such high-resolution simulations with a jointly developed novel version of the AMR grid code FLASH extended for the energy dependent anisotropic transport of CRs (ten energy bins) along magnetic field lines and taking into account adiabatic losses. We propose to extend the code with a module that allows for the self-consistent injection of CRs in strong shocks at rates derived from a computationally efficient and well tested semi-analytical model for non-linear diffuse shock acceleration. With these powerful tools and the two PhD positions that we apply for in this proposal we aim at addressing the following questions with three-dimensional MHD simulations for the first time: What is the global dynamical impact of cosmic rays generated in supernovae on the turbulent multi-phase structure of the ISM? How do cosmic rays at different energies diffuse through the turbulent magnetized ISM? Can cosmic rays support the launching of galactic winds in a realistically structured ISM? How does CR acceleration change the shock structure? How do the CRs diffuse away from shocks into the ISM? How do ionization and stellar winds of the SN progenitor change the shock structure and the CR injection? How does the CR acceleration vary for temporally and spatially coupled SNe? With the results of the proposed study we might very well prove that CRs do play a more significant role in shaping the ISM properties than previously thought. If we can confirm that CRs can actually drive large scale galactic outflows from a realistically structured ISM they will become a global player with a major role for shaping the ISM and regulating the formation efficiency of star forming galaxies at all masses and cosmic epochs.

宇宙射线（CR）是星际介质（ISM）的组成部分（非热）。它们很可能会在超新星爆炸产生的强冲击中加速，并沿磁场线传播到ISM中。由于能量损失率低，它们可以在大距离上运输，并且可以成为热量ISM气体的重要能量和动量来源（前提是它们可以对夫妇），也可以在低密度的区域中。分析和一维计算表明，CRS对ISM性质产生了重大影响，具有驱动大规模流出的潜力。这是通过近似星系尺度模拟表示的。然而，到目前为止，还没有对CRS对湍流ISM的动力学影响进行详细的磁性流动力学（MHD）模拟。我们建议使用沿磁场线的CRS（十个能量箱）的能量依赖性各向异性转运进行的共同开发的AMR网格代码闪光的新颖版本进行此类高分辨率模拟，并考虑到绝热损失。我们建议使用一个模块扩展代码，该模块允许以强烈的速率自动注入CRS，以从计算高效且经过良好测试的半分析模型得出，以用于非线性弥漫性冲击加速度。借助这些强大的工具和我们在本提案中申请的两个博士职位，我们旨在首次使用三维MHD模拟解决以下问题：超级新星在超新星对ISM湍流多相结构产生的宇宙射线产生的全球动力学影响是什么？不同能量处的宇宙射线如何通过湍流磁化ISM扩散？宇宙射线是否可以支持在结构化的ISM中发射银河风？ CR加速度如何改变冲击结构？ CRS如何从冲击中扩散到ISM？ SN祖细胞的电离和恒星风如何改变冲击结构和CR注入？ CR加速度在时间和空间耦合的SNE上有何不同？通过拟议的研究的结果，我们很可能会证明CRS在塑造ISM属性中的作用比以前想象的要重要。如果我们可以确认CRS实际上可以从现实结构的ISM中驱动大规模的银河流出，他们将成为全球玩家，在塑造ISM并调节所有群众和宇宙时期的星形形成星系的形成效率方面发挥了重要作用。