RUI: Collaborative Research: Beyond the Bulk Flow: Developing More Powerful Analysis Methods to Test Consistency of Large-scale Flows with the Standard Cosmological Model

长期以来，人们一直观察到，来自遥远星系的光在地球上被接收的波长与其发射时的波长不同。这种波长的漂移，通常被称为红移，是由两种截然不同的效应造成的，一种是星系相对于银河系运动产生的多普勒频移，另一种是光线在膨胀的空间中传播时产生的伸展。只有在能够获得星系距离的独立测量的情况下，这些效应才能被分离。然而，随着距离测量的数量和精度的提高，由于膨胀引起的漂移似乎比基于更大规模观测的预期要大得多。此外，对星系运动的研究揭示了大范围的流动也比预期的要大。该项目的目标是开发新的方法来分析现有的红移和距离测量，以便更好地理解数据和模型之间冲突的根源。特别是，研究人员试图确定这些分歧是由于测量中未发现的问题所致，还是他们确实指向了我们宇宙以前未知的方面。这里开发的数据分析技术将具有广泛的应用前景，并可能有助于推动其他领域的发展，特别是那些依赖于噪声数据的领域。该项目将通过向本科生提供数据分析和统计方面的密集研究经验和培训，加强美国的科学队伍，这些领域对美国的需求很高，具有战略重要性。此外，还将开发一门与拟议研究相关的编程课程，并在威拉米特学院向中学生讲授这门课程。威拉米特学院是一项面向与威拉米特大学相关的未被充分代表的学生的大学入学计划。随着星系距离测量的数量和精度的提高，它们作为对本地宇宙的宇宙学探测器变得越来越重要。然而，很明显，这一数据与微波背景辐射和标准宇宙模型的观测结果相矛盾。这项提议的目标是开发和应用新的统计方法来分析红移和距离测量的集合，也称为特殊速度星表，目的如下：(1)对宇宙学参数施加更强的约束；(2)更好地了解大尺度结构的动力学和宇宙的膨胀率；(3)在这类重要的宇宙学数据中测试系统学。这项拟议的研究将澄清红移和距离测量是否实际上与标准模型相冲突，如果是的话，分歧的严重性和来源。寻找膨胀速率测定和观测到的局部体积运动存在差异的原因，对于更全面地了解宇宙是很重要的。这些冲突的解决可能会带来新的物理学，或者在这个重要的宇宙学问题上更好地理解一些尚未确定的系统学。这一裁决反映了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。

It has long been observed that light from distant galaxies is received on earth at a different wavelength than that at which it was emitted. This shift in wavelength, often called redshift, is due to two distinct effects, the Doppler shift that arises from the motion of galaxies relative to the Milky Way and the stretching of light that is caused by its traveling through expanding space. These effects can be separated only if independent measurements of galaxy distances can be obtained. However, as the number and accuracy of distance measurements have improved, it appears that the shift due to expansion is significantly larger than expectations based on much larger scale observations. Furthermore, studies of the motions of galaxies have revealed large-scale flows that are also larger than expected. The goal of this project is to develop new ways of analyzing available redshift and distance measurements in order to better understand the sources of the conflict between the data and the model. In particular, the investigators seek to determine if the disagreements are due to undiscovered problems with the measurements or if they are indeed pointing the way toward a previously unknown aspect of our Universe. The data analysis techniques developed here will have broad application and may help advance other fields, particularly those that rely on noisy data. This project will strengthen the US science workforce by providing intensive research experiences and training to undergraduate students in data analysis and statistics, areas of high demand and of strategic importance to the nation. In addition, a programming course related to the proposed research will be developed and taught to secondary school students at Willamette Academy, a college access program for underrepresented students associated with Willamette University.As the number and accuracy of galaxy distance measurements have improved, they have become increasingly important as a cosmological probe of the local Universe. However, it has become apparent that this data is in conflict with observations of the microwave background radiation and the Standard Cosmological Model. The goal for this proposal is to develop and apply new statistical methods to analyze collections of redshift and distance measurements, also known as peculiar velocity catalogs, with the following goals: (1) to put stronger constraints on cosmological parameters; (2) to better understand the dynamics of the large-scale structure and the expansion rate of the Universe; and (3) to test for systematics in this important type of cosmological data. The proposed research will clarify whether redshift and distance measurements are actually in conflict with the Standard Model, and if so, the severity and source of the disagreement. Searching for the causes of the discrepancies in both the expansion rate determination and the observed motion of the local volume is important for gaining a more complete understanding of the Universe. A resolution of these conflicts may lead to new physics or to a better understanding of some yet-to-be-determined systematics in this important cosmological probe.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.