ELUCID - Exploring the Local Universe with Reconstructed Initial Density Field

附近的宇宙呈现出块状结构，如恒星和行星系统、星系和星系团，排列在一个美丽而复杂的宇宙网络中。遥远的早期宇宙看起来平滑得多。块状结构是如何从平滑的早期宇宙中形成的，这个问题仍然是一个令人兴奋的天体物理学之谜。此外，星系及其周围星系间介质的相互作用也是当前研究的热点。这个项目解决了关于140亿年宇宙历史中宇宙结构形成的重要问题。研究人员将试图回答的问题包括：是什么驱动了我们观察到的大规模结构的形成，以及像银河系这样的星系是如何在宇宙网络中形成和演化的？我们今天所理解的简单物理定律是否能够再现浩瀚宇宙中的复杂结构，以及它们之间的相互作用？该项目还将支持一名研究生在天体物理学、并行计算和计算机可视化方面的工作和专业培训。关于宇宙中物质（包括黑暗和可见）的时间演化的电影将被制作出来，让公众见证如何使用简单的物理原理来重现浩瀚宇宙中的复杂结构。研究人员将开发一种新的方法，使用数值模拟和半解析模型，来重建低红移宇宙中宇宙密度场演化的初始条件；利用重建的初始条件模拟暗物质和气体中的宇宙密度场；并研究星系、暗晕、暗物质和星系间介质之间的关系，以检验星系形成的理论。该方法的精度和可靠性将通过详细的数值模拟来量化。模拟将多次运行以探索宇宙变化。这项工作的输出将是一个模拟的SDSS目录，可用于直接探索观测和理论之间的比较。这项研究的结果将提供对形成星系和大规模结构的过程的见解，以及星系之间的关系，以及它们的环境和暗物质。

The nearby universe shows clumpy structures, such as stars and planetary systems, galaxies, and clusters of galaxies, arranged in a beautiful yet complex cosmic web. The distant, early universe appears much smoother. The question of how clumpy structures formed from a smooth early universe remains an exciting astrophysical mystery. Furthermore, the interaction of galaxies and their surrounding intergalactic medium is also a matter of intense current research. This project addresses important questions about the formation of structure in the universe over 14 billions years of cosmic history. The researchers will seek to answer questions that include: What drives the formation of the large-scale structure we observe and how do galaxies like the Milky Way form and evolve in the cosmic web?  Are simple physical laws as we understand today able to reproduce the complex structures in the vast cosmos, as well as their interaction with each other? The project will also support the work and professional training of a graduate student in astrophysics, parallel computing, and computer visualization. Movies about the time evolution of matter (both dark and visible) in the universe will be made to allow the public to witness how simple physical principles can be used to reproduce the complex structures in the vast cosmos.The researchers will develop a new method, using numerical simulations and semi-analytical modeling, to reconstruct initial conditions from which the cosmic density field in the low-redshift universe has evolved; simulate the cosmic density field in both dark matter and gas using the reconstructed initial conditions; and study the relationship between galaxies, dark halos, dark matter, and the intergalactic medium to test theories of galaxy formation. The accuracy of this new method and its reliability will be quantified using detailed numerical simulations. Simulations will be run multiple times to explore cosmic variance. An output from this work will be a mock SDSS catalog, available to explore the comparison between observations and theory directly. The results of this research will provide insight into the processes that shape galaxies and large-scale structures, as well as the relationship between galaxies, and their environments and dark matter.