Signatures of peculiar velocities in the cosmic microwave background

星系团特殊速度场的统计数据（即与宇宙膨胀无关的运动）对暗物质、暗能量和引力理论的本质提供了大量信息。目前，在大尺度上的特殊速度测量仅限于星系团的视距分量，使我们无法获得速度场中的大多数可用信息。未探测到的横向分量可以通过两种效应通过宇宙微波背景（CMB）来追踪：(i) CMB温度中的Birkinshaw-Gull （BG）效应，以及（ii） CMB极化中的动能Sunyaev-Zeldocivh （kSZ）效应。在这项研究中，我们对这些信号的可探测性进行了现实的评估，并研究了利用这些信号的统计数据进行宇宙学研究的可能性。PI将为K-12学生开发一个创造性的教育产品，以提高他们对物理学和宇宙学的认识和兴趣，特别是星系团和结构形成的物理学。K-12教师将接受培训，通过南加州大学学校大家庭利用现有关系使用这一教育产品。开发的材料也将提供给所有愿意下载和使用的教育工作者。BG和kSZ效应的振幅相对于主要的CMB各向异性和当前的仪器噪声水平是次要的。除此之外，这些信号可能会与来自星团内外的其他发射、引力透镜效应以及星团物理描述中的不确定性相混淆。因此，对单个物体观察这些效应几乎是不可能的。尽管如此，在数据分析中采用新颖的统计方法仍然有可能成功地发现它们。一个例子是使用两两统计估计器，这已被证明可以显着提高检测信噪比。在整个项目中，我们将研究在不久的将来使用下一代CMB调查测量这些信号的可能性。我们将通过半解析和数值模拟提供预测分析，并为此目的介绍适当的地图过滤技术和新的统计工具。目前，人们普遍对进行更大、更深入的CMB调查，提高强度和极化灵敏度，这使得现在是进一步研究特殊速度并检验其宇宙学含义的合适时机。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。

The statistics of the peculiar velocity field of galaxy clusters (i.e., motions not related to expansion of the universe) are highly informative about the nature of dark matter, dark energy, and the theory of gravity. Currently, peculiar velocity measurements on large scales are limited to only the line-of-sight components of clusters, leaving most of the available information in the velocity field inaccessible to us. The yet-undetected transverse components can be traced through the cosmic microwave background (CMB) via two effects: (i) the Birkinshaw-Gull (BG) effect in CMB temperature, and (ii) the Kinetic Sunyaev-Zeldocivh (kSZ) effect in CMB polarization. In this research, we make a realistic assessment of the detectability of these signals with the near future CMB experiments, and also investigate the possibility of exploiting the statistics of these signals for cosmology. The PI will develop a creative educational product for K-12 students to promote awareness of and interest in physics and cosmology, in particular the physics of galaxy clusters and structure formation. K-12 teachers will be trained to use this educational product leveraging on existing relationships via the USC family of schools. The developed material will also be available online for all educators willing to download and use it. The amplitude of both BG and kSZ effects are subdominant with respect to the primary CMB anisotropies and current instrumental noise levels. Aside from this, the signals can be confused with other emissions from within and outside the clusters, gravitational lensing effects, and uncertainties in clusters' physical description. Therefore, it is almost impossible to observe these effects for individual objects. Nevertheless, it is still possible to achieve a successful detection of them by employing novel statistical methods in the analysis of data. One example is to use pairwise statistical estimators which have been shown to significantly increase the detection signal-to-noise ratio. Throughout this project we will investigate the possibility of measuring these signals in the near future using the next generation of CMB surveys. We will provide forecast analyses through semi-analytical and numerical simulations of clusters and introduce proper map-filtering techniques and new statistical tools for this purpose. The current general interest in producing larger and deeper CMB surveys with improved intensity and polarization sensitivities makes this an appropriate time to further the study of peculiar velocities and inspect their cosmological implications.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.