Toward Precision Cosmology on Small Scales: A Data-Intensive Approach

有大量关于宇宙学和星系形成的小尺度编码信息，但相关的物理知识知之甚少，计算上也令人望而却步。基于晕的模型通过将星系和暗物质晕之间的关系参数化来绕过这个问题，但包含系统误差，并且不足以进行可靠的统计测试。该团队提出了一种新的数据密集型方法，使其在计算上变得容易处理，通过模拟构建现实的目录，并测量集群统计数据，就像对真实数据所做的那样。这项工作将超越概念验证，在小范围内对兰姆达-冷-暗物质(LCDM)宇宙学模型进行严格的测试。结果将是一个软件模拟器，它使用模拟网格来预测星系团统计数据作为宇宙学和星系晕参数的函数。所有的模拟目录和分析代码都将公开发布，这将使更多的项目成为可能。该项目还在目前的Fisk-Vanderbilt桥项目中增加了统计和数据分析关键领域的培训，该项目帮助来自代表性不足的群体的学生进入博士项目。目前的系统已经被用于测试固定的宇宙学模型，与斯隆数字天空调查中的测量结果相比，显示出与LCDM+HALO模型的最简单形式之间的显著紧张。这项下一项研究将通过确定最佳测量值、扩展星系-晕关系的参数化以考虑微妙的特征(包括非泊松统计、空间和速度偏差以及星系组合偏差)以及加强建模管道来进行。这将使对固定的宇宙学模型进行最严格的测试成为可能，并探索已添加的银河系-晕连接的微妙特征。该项目的最后一个雄心勃勃的部分是允许宇宙学参数在参数搜索范围内变化，方法是利用近似方法使用单一的宇宙学模拟来预测其他宇宙学的光晕分布。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

There is a wealth of information about both cosmology and galaxy formation encoded in small scales, but the relevant physics is poorly understood and computationally prohibitive. Halo-based models bypass this problem by parameterizing the relation between galaxies and dark-matter halos, but contain systematic errors and are not sufficiently accurate for reliable statistical tests. A new data-intensive approach that this team has made computationally tractable constructs realistic catalogs from simulations and measures clustering statistics exactly as is done for real data. This work will move past proof-of-concept to perform stringent tests of the Lambda-Cold-Dark-Matter (LCDM) cosmological model on small scales. The result will be a software emulator that uses a grid of simulations to predict galaxy clustering statistics as a function of both cosmology and galaxy-halo parameters. All mock catalogs and analysis codes will be publicly released, which will enable many additional projects. The project also adds training in the critical area of statistics and data analysis to the current Fisk-Vanderbilt bridge program that helps students from underrepresented groups move into a PhD program.The current system has already been used to test fixed cosmological models against measurements in the Sloan Digital Sky Survey, revealing significant tension with the simplest form of the LCDM plus halo model. This next study will be carried out by identifying optimal measurements, extending the parameterization of the galaxy-halo relation to allow for subtle features (including non-Poisson statistics, spatial and velocity bias, and galaxy assembly bias), and strengthening the modeling pipeline. This will enable the most stringent tests of fixed cosmological models, and probe those subtle features of the galaxy-halo connection that have been added. The final ambitious part of the project is to allow cosmological parameters to vary within the parameter search, by exploiting approximate methods to use a single cosmology simulation to predict the halo distributions of other cosmologies.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.