Modeling turbulent galaxy formation

伴随着星系形成的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，但是湍流对星系形成和相关过程的影响仍然在很大程度上未被探索。 该项目是利用自洽和现实的高分辨率宇宙学模拟系统地探索湍流及其对星系可观测特性的影响。 它将解决几个基本问题，在整个宇宙时间的星系观测的解释。 阿德勒天文馆将对计划的模拟使用高保真度、科学准确的可视化，适合全穹顶投影仪。 这些可视化将提供给其他天文馆，并通过日益普及的虚拟现实耳机进行在线流媒体和观看，这可以提供一种新的有效方式来接触社会的广泛阶层，包括学生和教育工作者，以引人入胜和易于访问的形式展示前沿研究的结果。这项工作是由该团队最近实施的亚网格湍流实现的，并将（1）研究在冷气体吸积流中是否会发展出滑动片不稳定性，以及湍流对关键性质的影响;（2）探索驱动湍流的引力不稳定性和恒星反馈;（3）量化湍流如何影响气体的密度结构、压力支持、星星形成和混合过程;（4）探索恒星初始质量函数（IMF）模型。 这些方法使用一种有效和多方面反馈的模型，包括由于宇宙射线、分子氢的形成、化学浓缩和演变以及电离和远紫外辐射的辐射转移而产生的反馈。 该研究探讨了关键问题，包括控制气体供应到星系的过程，星星和星星团形成效率的环境依赖性，以及不同恒星质量，金属丰度，形态和星星形成历史的星系中的IMF。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Cosmic gas flows accompanying galaxy formation have high velocities, span enormous scales, and are highly turbulent, but the effects of turbulence on galaxy formation and associated processes are still largely unexplored. This project is a systematic exploration of turbulence and its effects on the observable properties of galaxies using self-consistent and realistic high-resolution cosmological simulations. It will address several fundamental issues in the interpretation of observations of galaxies across cosmic time. The Adler Planetarium will use high-fidelity, scientifically-accurate visualizations of the planned simulations suitable for full-dome projectors. These visualizations will be available to other planetaria, and for online streaming and viewing with the increasingly widespread virtual reality headsets, which can provide a new and effective way to reach broad segments of society, including students and educators, showing the results of cutting-edge research in an engaging and easily accessible form.The work is enabled by a recent implementation of subgrid turbulence by this team, and will (1) investigate whether slip sheet instabilities develop in cold gas accretion flows, and the effect of turbulence on key properties; (2) explore gravitational instability and stellar feedback in driving turbulence; (3) quantify how turbulence affects the density structure of gas, pressure support, star formation, and mixing processes; and (4) explore models of the initial mass function (IMF) of stars. The methods use a model of efficient and multi-faceted feedback, including feedback due to cosmic rays, formation of molecular hydrogen, chemical enrichment and evolution, and radiative transfer of ionizing and far-ultra-violet radiation. The study explores key issues, including the processes controlling gas supply to galaxies, the environmental dependence of star and star cluster formation efficiency, and the IMF in galaxies of different stellar masses, metallicities, morphologies, and star formation histories.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.