Exploring the Structure of the Local Interstellar Medium with the Interstellar Boundary Explorer (IBEX)

该项目的目标是对最近提出的一个模型进行全面的定量评估，该模型解释了所谓的高能中性原子（ENAs）的增强微分通量带。根据这个模型，星际边界探测器（IBEX）在全天ENA通量图中探测到的条带是所谓的h波的结果，即从ISM传播到日球层的中性氢数密度的局部增强。相应的研究将以三种方式为当代关于外日球层和局部星际介质（ISM）的研究做出贡献，随着旅行者1号航天器最近进入星际空间，由于有机会对ISM进行原位测量，该研究再次受到关注：首先，该研究将有助于澄清IBEX带的性质。其次，它将限制本地ISM的物理性质（如星际磁场的方向和中性密度的变化）。第三，它将大大提高我们对太阳风与其星际环境相互作用的理解。该项目的主要目标是回答以下三个科学关键问题：（Q1）内日鞘质子速度分布对ENA光谱的影响是什么？（Q2）在自我一致模拟的“真实”日球层中，增强的差分ENA通量带是如何形成的？（Q3）在局部星际介质中，中性气体扰动的性质是什么？这些目标意味着相应的任务，即（T1）计算ENA种子种群（即质子）的速度分布，（T2）使用模拟日球层计算来自带状的ENA通量的差异，以及（T3）确定星际中性气体中扰动的性质。通过这些任务的完成，实现本项目的目标，不仅对当代最遥远的原位探测前沿的研究做出了上述三方面的贡献，而且通过约束局部ISM的状态和结构，有助于将日球层物理学和天体物理学之间一直存在的概念联系转化为实际的物理联系，可以认为是一般ISM的代表。

The goal of this project is a comprehensive quantitative assessment of a recently proposed model explaining the so-called ribbon of enhanced differential fluxes of energetic neutral atoms (ENAs). According to this model the ribbon, that was detected in the all-sky ENA flux maps with the Interstellar Boundary Explorer (IBEX) spacecraft, is a consequence of a so-called H-wave, i.e. a localized enhancement of the neutral hydrogen number density that is propagating from the ISM into the heliosphere. The corresponding study will contribute in a threefold way to the contemporary research regarding the outer heliosphere and the local interstellar medium (ISM) that -- with the recent entry of the Voyager~1 spacecraft into interstellar space -- received renewed attention due to the opportunity to make in situ measurements of the ISM: First, the study will contribute to clarify the nature of the IBEX ribbon. Second, it will constrain physical properties of the local ISM (such as the orientation of the interstellar magnetic field and neutral density variations). And, third, it will significantly improve our understanding of the interaction of the solar wind with its interstellar environment.The main objectives of the project is the answering of the following three scientific key questions: (Q1) What is the influence of the inner-heliosheath proton velocity distribution on the ENA spectra?, (Q2) How does the ribbon of enhanced differential ENA fluxes form in a self-consistently simulated 'realistic' heliosphere?, and (Q3) What are the properties of disturbances of the neutral gas in the local interstellar medium? These objectives imply corresponding tasks, namely (T1) the computation of the velocity distribution of the ENA seed population, i.e. protons, (T2) the computation of the differential ENA fluxes from the ribbon using a simulated heliosphere, and (T3) the determination the properties of disturbances in the interstellar neutral gas. With achieving the goal of the project by the completion of these tasks, we will not only make the mentioned threefold contribution to the contemporary research regarding the most distant frontier of in situ exploration, but help to transform the always existing conceptual link between heliospheric physics and astrophysics into an actual physical link by constraining the state and structure of the local ISM, which can be considered as representative for the general ISM.