Collaborative Research: Abacus: A New State-of-the-Art Cosmological N-body Code

该项目将进一步开发用于宇宙n体模拟的新计算机代码。Abacus实现了一种计算引力的新方法，比现有方法快100倍，而且精确得多。它可以在商品图形处理单元上运行，并提供了巨大的性价比改进。大尺度结构的观测调查依赖于宇宙学模拟来校准其统计估计器并计算精确的误差条，因此为了实现当前和未来宇宙学调查的潜力，必须运行大型高精度模拟网格。Abacus依赖于数学上的突破，实现了粒子近场力和远场力的清晰区分。目前的工作将增加对单个粒子时间步骤、动态组查找和合并树构建以及光锥输出的基本支持。该研究还将Abacus扩展到并行实现，并允许发布代码的公开版本。研究小组将使用Abacus进行第一套大型模拟，其结果光晕目录，合并树和光锥输出将公开，作为当前和未来调查项目的直接利益。Abacus改变了游戏规则，在对大型模拟的需求日益增加的时候，它为更多的天体物理学家提供了进行大型模拟的能力。Abacus的数学方法为椭圆方程的求解开辟了大量新的可能性，椭圆方程是广泛的科学和工程学科中最常见的计算任务之一。在此过程中，该项目将培养一名博士后研究员和一名研究生。

This project will further the development of a new computer code for cosmological N-body simulations. Abacus implements a novel method for computing gravitational forces that is a hundred times faster and substantially more accurate than current methods. It can be run on commodity graphics processing units and offers a vast improvement in price-performance. Observational surveys of large scale structure rely on cosmological simulations to calibrate their statistical estimators and compute accurate error bars, making it essential to run large grids of highly accurate simulations in order to realize the potential of current and future cosmological surveys. Abacus relies on a mathematical breakthrough that accomplishes a clean split between the near-field and far-field force on particles. The present work will add essential support for individual particle time steps, on-the-fly group finding and merger tree building, and light-cone outputs. The study will also extend Abacus to a parallel implementation, and allow release of a public version of the code.The research team will use Abacus for a first suite of large simulations, whose resulting halo catalogs, merger trees, and light-cone outputs will be made public as a direct benefit to current and future survey projects. Abacus is a game-changer, opening up the ability to do large simulations to many more astrophysicists at exactly the time that the need for large sets of large simulations will intensify. The mathematical approach of Abacus opens up substantial new possibilities in the solution of elliptic equations, one of the most common computational tasks across a wide range of scientific and engineering disciplines. Along the way, the project will train a post-doctoral researcher and a graduate student.