Toward Petascale Cosmology with GADGET

数值模拟现在是理论宇宙学的主要工具。随着计算机能力和软件算法的不断进步，以高质量和高空间分辨率模拟整个可见宇宙将成为可能。该项目将采用高效、低风险的增量策略，开发重力/流体力学代码GADGET的一个新的千万亿级优化版本。GADGET是最广泛使用的宇宙模拟代码。混合共享内存、负载平衡和其他改进将允许新的p-GADGET在（数量级）一百万个核上运行。p-GADGET将应用于两个基本问题，而目前的数值方法对这两个问题的解差达千分之一。这包括第一个流体动力学模拟，能够研究大量类星体和星系的形成，从最小的到最稀有的和最明亮的，使用经过良好测试的恒星形成、黑洞形成、吸积和反馈算法。p-GADGET还将创建终极暗物质模拟，通过模拟每一个拥有星系的单个团块来完全解决暗物质晕的质量函数。将这些结果与我们观测到的宇宙相匹配，将表明我们是否完全理解暗物质对宇宙学的天体物理影响。GADGET的公开版本取得了巨大的成功。p-GADGET也将类似地公开提供，向广大受众开放高效的千兆级科学领域，并大力增加首批千兆级计算机的用户基础。模拟结果也将普遍可供任何人使用：利用千兆级资源产生的模拟中的细节和大量信息，将需要一个极其广泛的研究人员基础。这种对宇宙结构如何在大范围内形成的新理解，以及伴随的可视化，将为一个广泛的推广项目提供信息，包括高中生、在科学领域代表性不足的少数民族中学生、本科课程项目和公开演讲。

OCI-0749212Di MatteoNumerical simulations are now the dominant tool in theoretical cosmology. As advances in computer power and software algorithms continue into the petascale regime, it will become possible to simulate the entire visible universe at high mass and spatial resolutions. This project will develop a new, petascale-optimized version of the gravity/hydrodynamics code GADGET, the most widely used cosmological simulation code, using an efficient and low-risk incremental strategy. Hybrid shared memory, load balancing and other improvements will allow the new p-GADGET to run on (of order) a million cores. p-GADGET will be applied to two fundamental problems for which current numerical methods fall short by a factor of a thousand. This includes the first hydrodynamical simulation capable of studying the formation of the vast range of quasars and galaxies, from the smallest to the rarest and most luminous, using well-tested algorithms for star formation, black hole formation, accretion, and feedback. p-GADGET will also create the ultimate dark matter simulation, one that fully resolves the mass function of dark matter halos by modeling every single clump that hosts a galaxy. Matching these results to our observed Universe will show whether or not we fully understand the astrophysical impact of dark matter on cosmology.The public version of GADGET has been wildly successful. p-GADGET will similarly be publicly available, opening up the domain of efficient petascale science to a wide audience, and adding strongly to the user base of the first petascale machines. The simulation outputs will also be generally available for use by anyone: an extremely broad base of researchers will be necessary to exploit the detail and enormous amount of information in simulations produced with petascale resources. This new understanding of how structure forms in the Universe on a wide range of scales, with accompanying visualizations, will inform an expansive outreach program, including high school students, middle school students from minorities under-represented in science, undergraduate coursework projects, and public presentations.