Collaborative Research: Toward Petascale Simulations of Early Cosmic Evolution

AST-0708960/0707505/0708309Norman/Ostriker/RicottiThis是一个由诺曼博士领导的三项合作项目，旨在利用未来千万亿级超级计算机的能力，在具有宇宙学代表性的体积中对早期结构形成进行自洽模拟。天文学家对未来主要设施将在高红移(7以上)下观测到的东西的预期，主要是基于标准的Lambda-CDM宇宙学框架中宇宙结构早期增长的理论和数值模型。新的模拟将使用专门为Petascale计算机开发的自适应网格细化(AMR)技术，跨越局部和全球尺度。这使得能够模拟100亿个粒子，10万个空间动态范围，以及包括辐射和化学反馈在内的复杂重子物理。由于目前理论很难受到观察的约束，同样重要的努力将是对不确定性量化和敏感性分析的严格尝试。因此，这项研究将使用运行在最强大的计算机上的最完整的物理模型来解决宇宙学中的前沿问题，并使用最佳实践进行分析。其结果将是早期宇宙演化的全面模型以及对其预测价值的严格评估。这项工作将极大地推进数值多物理宇宙模拟的最新水平，预计将继续先前代码可用性在天体物理界内外的成功影响。新的Petascale方法也将在通常的天文学圈子之外进行宣传，Enzo社区代码的增强版本将向公众发布。此外，数值结果和综合观测结果都将利用国家虚拟天文台提供的机制向国际研究界公布。

AST-0708960/0707505/0708309Norman/Ostriker/RicottiThis is a three-award collaborative project, led by Dr Norman, to harness the power of future petascale supercomputers for self-consistent simulations of early structure formation in cosmologically representative volumes. Astronomers' expectation of what will be observed at high redshifts (above 7) by future major facilities is largely based on theoretical and numerical models of the early growth of cosmic structure in a standard Lambda-CDM cosmological framework. The new simulations will span local and global scales using adaptive mesh refinement (AMR) technology developed specifically for petascale computers. This enables simulations with ten billion particles, a spatial dynamic range of a hundred thousand, and complex baryonic physics including radiative and chemical feedback. As theories are at present poorly constrained by observations, an equally important effort will be a rigorous attempt at uncertainty quantification and sensitivity analysis. The study will thus address forefront questions in cosmology using the most complete physical models running on the most powerful computers, analyzed using best practices. The result will be comprehensive models of early cosmic evolution along with a rigorous assessment of their predictive value.This work will substantially advance the state-of-the-art in numerical multi-physics cosmological simulations, which can be expected to continue previous successful impacts of code availability, both within and outside of the astrophysics community. The new petascale methodologies will also be publicized well outside the usual astronomy circles, and the enhanced version of the Enzo community code will be released to the public. In addition, both the numerical results and the synthetic observations will be published to the international research community using mechanisms provided by the National Virtual Observatory.