标题： 通过运动学苏尼亚耶夫-泽尔多维奇效应测量X射线星系团的整体运动：总结“暗流”证据及其影响 显示英文标题

标题： Measuring bulk motion of X-ray clusters via the kinematic Sunyaev-Zeldovich effect: summarizing the "dark flow" evidence and its implications

摘要： 在本次综述中，我们对最近使用X射线星系团作为示踪剂，通过一种新方法测量的非常大尺度上的特殊速度场进行了全面讨论。 该测量基于宇宙微波背景（CMB）光子与星系团内热气体发生康普顿散射所产生的太阳亚夫-泽尔多维奇（KSZ）效应的动力学分量，并利用了由X射线选择的大量星系团目录以及通过WMAP卫星获得的全天CMB图谱。 该方法探测的是在星系团位置和CMB单极子贡献消失的孔径内评估的CMB温度场的偶极子，从而隔离出由相干运动星系团产生的KSZ效应的剩余信号。 在至少约800 Mpc深度范围内检测到一个高度显著的偶极子，这引发了对引力不稳定性的质疑，即从观测到的质量分布产生的引力不稳定是否是检测到的运动的唯一——甚至主要——原因。 相反，似乎流动可能延伸至整个可观测宇宙。 可能的含义包括限制时空的原始暴胀前结构及其景观的可能性，以及需要对目前已知物理进行修改（例如，由于引力的高维结构而产生）。 我们根据此处描述的测量结果回顾了这些可能性，并特别讨论了未来测量的前景以及它们应解决的问题。 我们探讨了这些大尺度速度测量与使用星系作为示踪剂的研究在较小尺度上获得的测量结果的一致性，并解决了基于修改后的CMB分析方案的两个近期声明之间的差异。 显示英文摘要

摘要： In this review we present a comprehensive discussion of peculiar velocity field measured recently on very large scales with a novel method using X-ray galaxy clusters as tracers. The measurement is based on the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background (CMB) photons off the hot intracluster gas, and uses a large catalog of X-ray selected clusters and all-sky CMB maps obtained with the WMAP satellite. The method probes the dipole of the CMB temperature field evaluated at the cluster positions and within the apertures in which the CMB monopole contribution vanishes, thereby isolating the signal remaining from the KSZ effect produced by coherently moving clusters. The detection of a highly significant dipole out to the depth of at least ~ 800 Mpc casts doubt on the notion that gravitational instability from the observed mass distribution is the sole -- or even dominant -- cause of the detected motions. Rather it appears that the flow may extend across the entire observable Universe. Possible implications include the possibility to constrain the primeval preinflationary structure of space-time and its landscape, and/or the need for modifications of presently known physics (e.g. arising from a higher-dimensional structure of gravity). We review these possibilities in light of the measurements described here and specifically discuss the prospects of future measurements and the issues they should resolve. We address the consistency of these large-scale velocity measurements with those obtained on smaller scales by studies using galaxies as tracers, and resolve the discrepancies with two recent claims based on modified CMB analysis schemes.