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

合作研究：超越整体流动：开发更强大的分析方法来测试大规模流动与标准宇宙学模型的一致性

• 批准号: 1907404
• 负责人: Hume Feldman
• 金额: $ 23.27万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1907404&HistoricalAwards=false
• 关键词: Collaborative; Research; Beyond; Bulk; Flow

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.

人们早就观察到，来自遥远星系的光在地球上接收到的波长与发射时的波长不同。这种波长的变化，通常被称为红移，是由两种不同的效应引起的，一种是星系相对于银河系运动产生的多普勒频移，另一种是光在膨胀的空间中传播所引起的拉伸。这些效应只有在能够获得星系距离的独立测量时才能分离出来。然而，随着距离测量的数量和精度的提高，由于膨胀引起的偏移似乎比基于更大尺度观测的预期要大得多。此外，对星系运动的研究也揭示了比预期更大的大规模流动。该项目的目标是开发新的方法来分析可用的红移和距离测量，以便更好地了解数据和模型之间冲突的来源。特别是，研究人员试图确定这些分歧是由于测量中未被发现的问题，还是它们确实指向了我们宇宙中一个以前未知的方面。这里开发的数据分析技术将有广泛的应用，并可能有助于推进其他领域，特别是那些依赖于噪声数据的领域。该项目将通过为数据分析和统计领域的本科生提供密集的研究经验和培训，加强美国的科学劳动力，这些领域对国家具有高需求和战略重要性。此外，将为威拉米特学院（Willamette Academy）的中学生开设一门与拟议研究相关的编程课程，这是威拉米特大学（Willamette University）为代表性不足的学生开设的大学入学课程。随着星系距离测量的数量和精度的提高，它们作为局部宇宙的宇宙学探测器变得越来越重要。然而，很明显，这些数据与微波背景辐射和标准宇宙学模型的观测结果相冲突。该提案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，也称为特殊速度表，其目标如下：(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)检验这类重要的宇宙学数据的系统性。拟议的研究将澄清红移和距离测量是否真的与标准模型相冲突，如果是的话，分歧的严重程度和来源。寻找膨胀率测定和观测到的局部体积运动之间差异的原因对于获得对宇宙更全面的理解是重要的。这些冲突的解决可能会导致新的物理学或更好地理解一些尚未确定的系统在这个重要的宇宙探索。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Improved Methods for Estimating Peculiar Velocity Correlation Functions Using Volume Weighting

• DOI: 10.3847/1538-4357/ac0e37
• 发表时间: 2021-08
• 期刊: The Astrophysical Journal
• 作者: Yuyu Wang;S. Peery;H. Feldman;R. Watkins

Analysing the large-scale bulk flow using cosmicflows4: increasing tension with the standard cosmological model

使用 cosmicflows4 分析大规模整体流：使用标准宇宙学模型增加张力

• DOI: 10.1093/mnras/stad1984
• 发表时间: 2023
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Watkins, Richard;Allen, Trey;Bradford, Collin James;Ramon, Jr, Albert;Walker, Alexandra;Feldman, Hume A.;Cionitti, Rachel;Al-Shorman, Yara;Kourkchi, Ehsan;Tully, R. Brent
• 通讯作者: Tully, R. Brent

Peculiar velocity estimation from kinetic SZ effect using deep neural networks

• DOI: 10.1093/mnras/stab1715
• 发表时间: 2020-10
• 期刊: arXiv: Cosmology and Nongalactic Astrophysics
• 作者: Yuyu Wang;Nesar Ramachandra;Edgar M. Salazar-Canizales;H. Feldman;R. Watkins;K. Dolag