Cosmic Structures: from Cosmology to Interstellar Medium

这项建议涵盖了天体物理湍流的统计研究和丝状宇宙网理论及其在星系和星系团属性中的作用的研究计划。 湍流和磁场在许多关键的天体物理过程中起着关键作用。确定湍流运动中的能量分布、磁场的强度、取向和标度、能量注入和耗散的特征尺度、不可压缩模和可压缩模的相对强度对于理解恒星形成、星际和星团内介质中的热输运、宇宙线的加速等基本天体物理过程至关重要。在我们的银河系中，在其他星系或星系团中，磁场被复杂的等离子体湍流运动所携带，这导致了作为多普勒频移谱线或漫射同步辐射发射的光的强度和偏振的特征关联。从这样的观测中解开磁化湍流的定量特性是一项复杂的任务。我们正在开发严格的统计方法，基于磁化湍流的现代模型，并针对各种可观测数据来实现这一点。 宇宙学家现在对我们宇宙中结构形成的整体图景充满信心。我们宇宙的复杂性来自于宇宙迅速膨胀的早期时期物质的微小量子涨落。后来，在重力的作用下，不均匀物质成长为恒星、星系，并在大尺度上形成了星系网，在宇宙微波背景上留下了印记。在早期，暗物质和气体分布的丝状网络被证明影响星系的形成，而现在它定义了星系团间的环境。我们将从理论和数值上研究丝状图案的连通性，因为它从初始条件演变到银河系，然后是星系团尺度。我们的目标是回答这样的问题，如有多少细丝加入星系团，这是否取决于星系团的性质，它是否告诉我们星团是如何组装的，细丝臂有多长，细丝是形成一个连续的网络还是不相交的，这些参数是如何根据宇宙学模型在时间上演化的；并通过这种方式，获得对宇宙结构的更完整的描述和理解。我们还将通过建立大尺度结构中晕自旋分布的详细统计理论，研究处于丝状环境中的星系对星系性质的影响，特别是对其自旋的影响，这将有助于理解星系的形成和对未来星系调查的解释。

This proposal covers research programs in statistical studies of astrophysical turbulence and in the theory of the filamentary Cosmic Web and its role in the properties of galaxies and clusters of galaxies. Turbulence and Magnetic fields play critical role in many of the key astrophysical processes. Determining energy distribution in turbulent motions, strength, orientation and scaling of the magnetic fields, characteristics scales of energy injection and dissipation, relative strength of incompressible and compressible modes are of vital importance for understanding fundamental astrophysical process such as star formation, heat transport in interstellar and intra-cluster medium, acceleration of cosmic ray. In our Galaxy, in other galaxies, or in clusters of galaxies, magnetic fields are found to be carried around by complex turbulent motions of plasma, which results in characteristic correlations in the intensity and polarization of light emitted as Doppler shifted spectral lines or diffuse synchrotron radiation. Disentangling the quantitative properties of the magnetized turbulence from such observations is a complex task. We are developing rigorous statistical methods, based on modern models of the magnetized turbulence, and for a variety of observable data, to accomplish it. Cosmologists are now confident in the overall picture of structure formation in our Universe. The complexity of our Universe came from tiny quantum fluctuations of matter at the very early era when the Universe rapidly inflated. Inhomogeneities later grew under the force of gravity into stars, galaxies and, at large scales, the galactic Web, leaving along the way the imprint on the Cosmic Microwave Background. At the earlier epoch the filamentary Web of dark matter and gas distribution was shown to affect the formation of the galaxies, while at present time it defines the inter-cluster environment. We shall study theoretically and numerically the connectivity of the filamentary pattern as it evolves from initial conditions to galactic and then cluster scales. Our goal is to answer questions such as how many filaments join the cluster, does this depend on the cluster properties, does it tell us how cluster was assembled, how long are filament arms, do filaments form a connected network or are disjoint, how these parameters evolve in time depending on a cosmological model; and, in this way, obtain a more complete description and understanding of the structure in the Universe. We will also investigate the effect being in filamentary environment has on galaxy properties, and in particular their spin by working towards detailed statistical theory of halo spin distribution within the large scale structures, that would be beneficial for understanding galaxy formation and for interpretation of the future galactic surveys.