Intrinsic Alignment Models for Precision Cosmology

现代宇宙学中的一个关键谜团是暗能量的性质，它是导致我们宇宙加速膨胀的原因。弱引力透镜是揭示暗能量本质的最有前途的观测方法，它是由于光线质量偏转而导致的星系形状的相干扭曲。因此，即将进行的大型观测，如大型天气观测望远镜(LSST)，计划非常精确地测量弱透镜。该项目的目标是提供准确的理论预测，消除弱透镜测量中的一个关键不确定性来源，并测试它们在分析正在进行的天空测量数据中的使用情况。这样的工作将有助于解开现代宇宙学中最大的谜团，显然将促进科学的进步。作为一个额外的好处，调查人员将把现有的、非常成功的教育外展计划(“太空公共外展团队”或Spot)扩展到匹兹堡地区，重点关注少数族裔比例较低的学校。该项目将对K-12教育以及本科生和研究生教育产生影响。弱引力透镜在解决宇宙学中的一些重大悬而未决的问题方面具有巨大的潜力，例如暗能量的性质。然而，不确定性的一个主要来源是，这些测量结果通常被解释为假设所有相干的星系形状对齐都是由于弱透镜，但不幸的是，星系确实表现出与大尺度密度场的一致的“内在对齐”。对准对弱透镜测量的污染程度将大大超过LSST弱透镜测量的统计误差条。这个项目有三个主要目标。第一个目标是使用大体积、极高分辨率的流体动力学模拟来加深我们对内在比对背后的物理原理的理解，并建立改进的内在比对模型。第二个目标是制作具有内在排列的模拟星系星表，用于测试内在排列缓解方案。最终目标是进行宇宙学弱透镜分析，包括使用改进的本征对准模型对本征对准进行边缘化的策略，这些改进的本征对准模型受到最先进的模拟、分析理论和观测的推动。

One of the key mysteries in modern cosmology is the nature of the dark energy that is responsible for the accelerated expansion rate of our Universe. Weak gravitational lensing, the coherent distortion of galaxy shapes due to deflection of light by mass, is the most promising observational method for uncovering the nature of dark energy. As a result, large upcoming surveys such as the Large Synoptic Survey Telescope (LSST) have been planned to measure weak lensing very precisely. The objective of this project is to provide accurate theoretical predictions that will eliminate a key source of uncertainty in weak lensing measurements and test their use in analysis of data from an ongoing sky survey. Work such as this, that will contribute to the solution of the biggest mystery in modern cosmology, will clearly promote the progress of science. As an additional benefit, the investigators will extend an existing, highly successful educational outreach program ("Space Public Outreach Team" or SPOT) to the Pittsburgh area, focusing on schools with a significant fraction of under-represented minorities. This project will have an impact both on K-12 education and undergraduate and graduate education.Weak gravitational lensing has great potential to solve some of the major outstanding issues in cosmology, such as the nature of dark energy. However, a major source of uncertainty is that these measurements are typically interpreted assuming that all coherent galaxy shape alignments are due to weak lensing, but unfortunately, galaxies do exhibit coherent "intrinsic alignments" with large-scale density fields. The alignments contaminate weak lensing measurements at a level that will significantly exceed the statistical error bars on weak lensing measurements with the LSST. This project has three main objectives. The first objective is to use large volume, extremely high resolution hydrodynamic simulations to further our understanding of the physics behind intrinsic alignments and build improved intrinsic alignments models. The second objective is to produce mock galaxy catalogs with intrinsic alignments for use in testing intrinsic alignments mitigation schemes. The final objective is to carry out cosmological weak lensing analysis including strategies to marginalize over intrinsic alignments using improved intrinsic alignment models that are motivated by state-of-the-art simulations, analytic theory, and observations.