COLLABORATIVE RESEARCH: New Frontiers in Galaxy Formation Modeling

AST-0708154/0708087Kravtsov/GnedinUnderstanding星系的形成是现代宇宙学中最重要和最具挑战性的问题之一。特别是，恒星形成可能是现代宇宙学模拟中最不被理解和最不发达的组成部分。这个由Kravtsov博士领导的合作项目旨在通过开发新的、受观测激励的恒星和星团形成模型，极大地减少星系形成物理上的不确定性。最近在数值算法和计算能力方面的进步意味着，宇宙流体动力学模拟现在可以解决星际介质中恒星形成的实际位置，从而有可能自我一致地跟踪巨型分子云的形成和破坏。计划中的一套超高分辨率N体和气体动力学自适应网格细化模拟将包括前所未有的丰富的物理过程，包括分子氢在尘埃上的形成及其对环境紫外线辐射的自我屏蔽，以及自洽的三维连续辐射传输。在较小的尚未解决的尺度上，模拟将纳入基于可靠的经验关联的恒星形成配方。计划中的研究将研究高红移星系的分子含量，开发与观测关联一致的恒星形成处方，并研究不同星系环境中的恒星形成。该项目将解决大质量星团的形成和演化问题，其中有丰富的观测数据，并研究星团形成效率与宿主星系性质的关系。该项目的独特之处在于它能够连接大尺度的星系形成和小尺度的恒星形成，从而发展这两个研究界之间的联系。通过让学生参与，这项工作为年轻的计算宇宙学家提供了尖端模拟技术的专业培训。这一结果为目前和即将实施的天基和陆基观测计划提供了支持。研究成果紧密结合到学术教学、公众教育和外展活动中。模拟的三维可视化将在天文馆展览和公开演讲中使用，也可以通过网络访问。

AST-0708154/0708087Kravtsov/GnedinUnderstanding galaxy formation is one of the most important and challenging problems in modern cosmology. In particular, star formation is perhaps the worst understood and least developed ingredients of modern cosmological simulations. This collaborative project, led by Dr Kravtsov, aims to reduce greatly the uncertainty in the physics of galaxy formation by developing new, observationally motivated models for the formation of stars and star clusters. Recent advances in numerical algorithms and computing power mean that cosmological hydrodynamical simulations can now resolve the actual sites of star formation in the interstellar medium, making it possible to track the formation and destruction of giant molecular clouds self-consistently. The planned suite of ultra high-resolution N-body and gas dynamic adaptive mesh refinement simulations will incorporate an unprecedented wealth of physical processes, including the formation of molecular hydrogen on dust and its self-shielding from ambient ultraviolet radiation, and self-consistent three-dimensional continuum radiative transfer. On smaller unresolved scales, the simulations will incorporate star formation recipes based on reliable empirical correlations. The planned research will study the molecular content of high-redshift galaxies, develop star formation prescriptions consistent with the observational correlations, and study star formation in different galactic environments. It will address the formation and evolution of massive star clusters, for which abundant observational data exist, and investigate the dependence of cluster formation efficiency on properties of the host galaxy.This project is unique in its ability to bridge the large scales of galaxy formation and the small scales of star formation, thus developing links between those two research communities. By involving students, the work provides professional training of young computational cosmologists in cutting-edge simulation techniques. The results provide support for current and forthcoming space- and ground-based observing programs. The research results are tightly integrated into academic teaching, and public education and outreach activities. Three-dimensional visualizations of the simulations will be available for planetarium shows and public lectures, and also web-accessible.