Collaborative Research: Modelling the Turbulent Galaxy Formation

任何有流体运动的地方，无论是液体还是气体，都会有湍流。 这些对流动的干扰可能非常重要，但它们对宇宙气体形成星系的可能深远影响仍然是我们对宇宙如何演化的基本理解中的一个谜。 这项工作旨在纠正这一不足，使用高性能计算机进行新的数值模拟，具有非常高的分辨率。 这是第一次，几乎所有涉及星系内恒星形成的物理学都将被包括在内。 计算将与望远镜数据密切相关，既检查计算机结果，又有助于理解观测结果。 这些新的想法也将对湍流流体的其他研究有用。宇宙气体流具有很高的速度，跨越巨大的尺度，并且是高度湍流的，但湍流对星系形成可能产生的深远影响在很大程度上尚未探索。 该项目是一个系统的探索湍流及其对吸积流，星星的形成，和星系的结构，在自洽的宇宙学模拟使用自适应网格细化（AMR）。 部分工作将实施和测试一种新的亚网格尺度湍流模型，并使用它来估计局部湍流应力。 该模型将用于在星系形成模拟中增加新的物理驱动的星星形成处方，纳入一套丰富的物理过程，这些过程被认为是与观测进行比较的关键，包括分子氢的建模，化学富集和演变，尘埃的形成和破坏，电离和远紫外辐射的辐射转移，星星形成，以及辐射压力和宇宙射线的恒星反馈。 观测比较将测试和告知理论模型，而模拟结果将有助于理解数据。 科学成果将包括量化湍流对进入星系的冷吸积气体流的影响，评估湍流动力驱动因素的相对贡献，以及量化湍流对气体密度结构的影响。 对观测比较的强调将使这项研究对解释当前和未来设施的结果特别有价值。 本文的方法和结果对其它模拟和半解析模型都有参考价值。 这些模拟也很好地适合于高保真，科学准确的可视化，非常适合全圆顶天文馆投影仪的高分辨率环境，但对所有天文馆都有价值。

Anywhere that there is a fluid in motion, whether liquid or gas, there will be turbulence. These disturbances to the flow can be very significant, but their possibly profound effect on the formation of galaxies out of the cosmic gas remains an area of mystery in our fundamental understanding of how the Universe evolves. This work seeks to correct this lack, using high powered computers to carry out novel numerical simulations with very high resolution. For the first time, pretty well all of the physics involved in forming stars within galaxies will be included. The calculations will be intimately connected with telescope data, both checking the computer results and helping to understand the observations. The new ideas will also be useful for other studies of turbulent fluids.Cosmic gas flows have high velocities, span enormous scales, and are highly turbulent, but the possibly profound effects of turbulence on galaxy formation are largely unexplored. This project is a systematic exploration of turbulence and its effects on accretion flows, star formation, and the structure of galaxies, in self-consistent cosmological simulations using adaptive mesh refinement (AMR). Part of the work will implement and test a novel model for sub-grid scale turbulence and use it to estimate local turbulent stresses. This model will be used to add new physically-motivated prescriptions for star formation into the galaxy formation simulations, incorporating a rich set of physical processes thought to be critical for comparison with observations, including modeling of molecular hydrogen, chemical enrichment and evolution, dust formation and destruction, radiative transfer of ionizing and far-ultraviolet radiation, star formation, and stellar feedback with radiation pressure and cosmic rays. Observational comparisons will test and inform the theoretical models, while the simulation results will help to understand the data. Scientific results will include quantifying the effects of turbulence on the cold accretion gas flows onto galaxies, assessing the relative contribution of dynamical drivers of turbulence, and quantifying the effects of turbulence on the density structure of the gas. The emphasis on observational comparisons will make this study particularly valuable for interpreting the results from current and future facilities. Both the methods and the results will be of value for other simulations and for semi-analytic models. The simulations also lend themselves well to high-fidelity, scientifically-accurate visualizations well suited to the high resolution environment of full-dome planetarium projectors, but of value to all planetaria.