Cosmic Ray Anisotropy and Interstellar Spectra: Astrophysics of the Outer Heliosphere

利用地面和空间探测器进行的各种测量揭示了正确理解日光层物理学的天体物理学意义。对拟议的项目来说，最重要的是与日光层外层空间有关的观测。首先，利用旅行者号航天器不断改进宇宙射线的局部星际光谱的测定。第二，旅行者号，特别是IBEX使命，增加了我们对本地星际磁场、等离子体和日光层周围中性气体的定量知识。第三，在低TeV范围内观测到的宇宙线各向异性部分是由日光层结构引起的假设，最近得到了几个地面大面积粒子探测器和望远镜测量的新支持，以及从理论上考虑，例如，在heliotail的磁重联。为了判断各种建议的正确的物理描述的外部日光层和它的天体物理学的相关性，我们将开发定量模型占日光层及其星际附近的大尺度结构，特别是包括所谓的日鞘和日尾以及本地星际磁场。因此，本提案的主要目标定义如下：我们将通过自洽地包括磁场来扩展我们以前对嵌入星际介质中的大尺度日光层的建模-特别是关于高度拉长的日光层尾部-我们将通过求解这些粒子的传输方程和运动方程来研究相应的宇宙射线通量。因此，我们可以测试是否heliotail确实影响各向异性的宇宙射线通量在低TeV范围内。此外，该模型还允许我们研究日球外层结构对星际宇宙线谱的影响。对于这些应用，我们将引入新的，所谓的逻辑矩形网格日光层建模，因为目前使用的有严重的缺点。这些新的网格具有局部可调的问题的几何形状，避免了坐标奇异性和强烈不同的细胞大小的优点。该项目的成果将包括对我们的直接天体物理环境进行建模，这将首次允许对天体物理观测中潜在的日光层特征进行定量解释。

Various measurements with ground- and space-based detectors have revealed the astrophysical relevance of a correct understanding of heliospheric physics. Most important for the proposed project are those observations related to outer bundary of the heliosphere. First, the determination of the local interstellar spectra of cosmic rays is improved continuously with the Voyager spacecraft. Second, the Voyagers and, particularly, the IBEX mission have increased our quantitative knowledge about the local interstellar magnetic field, plasma, and neutral gas surrounding the heliosphere. Both have triggered a refined understanding of cosmic ray modulation.Third, the hypothesis that the observed cosmic ray anisotropy in the low-TeV range is partly caused by the heliospheric structure, has recently gained new support from measurements with several terrestrial large area particle detectors and telescopes, as well as from theoretical considerations regarding, for example, magnetic reconnection in the heliotail. In order to judge on the various suggestions for the correct physical description of the outer heliosphere and its astrophysical relevance, we will develop quantitative models accounting for the large-scale structure of the heliosphere and its interstellar vicinity, particularly including the so-called heliosheath and heliotail as well as the local interstellar magnetic field. Consequently, the main objectives of the present proposal are defined as follows: We will extend our previous modelling of the large-scale heliosphere embedded in the interstellar medium by self-consistently including magnetic fields - especially with respect to the highly elongated heliospheric tail - and we will study the corresponding cosmic ray flux by solving both the transport equation and the equation of motion for these particles. Thus, we can test whether the heliotail indeed affects the anisotropy of the cosmic ray flux in the low-TeV range. Furthermore, this model allows us to study the effect of outer heliospheric structures on the local interstellar cosmic ray spectra. For these applications we will introduce new, so-called logically rectangular grids into heliospheric modelling since the presently used ones have severe shortcomings. These new grids have the advantages of being locally adjustable to the problem's geometry, avoiding both coordinate singularities and strongly differing cell sizes. The project results will consist of a modelling of our direct astrophysical environment, that will allow, for the first time, a quantitative interpretation of potential heliospheric signatures in astrophysical observations.