Galaxy Cluster Velocities and Cosmology

从阿塔卡马宇宙学望远镜(ACT)和南极望远镜(SPT)等实验开始，高分辨率和高灵敏度的微波天空测量才刚刚开始。他们将通过被称为Sunyaev-Zeldovich效应(SZE)的微波背景辐射的光谱扭曲来探测数以千计的星系团。这些实验具有使用被称为动力学SZE(KSZ)的小信号来测量星系团速度的显著潜力，这将是第一次直接确定宇宙距离处物体的速度。由于速度是引力不稳定的直接结果，因此宇宙速度场是结构生长的有力探测器。由于较大的系统误差，早期研究通常没有定论。这个项目是对星系团速度的全面的理论、唯象和观测研究，包括(1)宇宙学信息的表征；(2)提取宇宙信息的统计方法；(3)计算系统误差的影响；(4)改进星系团速度和动量统计模型预测的计算；(5)研究从不同波段的观测中提取星系团速度和动量的精度；以及(6)从ACT实验中提取星系团特有的速度和动量。这个新获得的宇宙学信息来源是对宇宙结构形成的新探索，提供了宇宙学标准模型的独立测试，并更好地确定了几个基本参数。该项目包括一系列层面的教育举措，包括指导研究生；让本科生参与研究工作；以及与阿勒格尼天文台合作开展中学教育和公共宣传工作。

High-resolution and high-sensitivity microwave sky surveys are just beginning, from experiments such as the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT). They will detect thousands of galaxy clusters through the spectral distortion of the microwave background radiation known as the Sunyaev-Zeldovich Effect (SZE). These experiments have the remarkable potential to measure galaxy cluster velocities using a small signal known as the kinetic SZE (kSZ), which would be the first direct determination of velocities for objects at cosmological distances. The cosmic velocity field is a powerful probe of structure growth, since velocities are the direct result of gravitational instability. Early studies were generally inconclusive because of large systematic errors. This project is a comprehensive theoretical, phenomenological, and observational study of galaxy cluster velocities, including (1) characterization of the cosmological information; (2) statistical methods for extracting it; (3) calculating the impact of systematic errors; (4) improved calculations of model predictions for the cluster velocity and momentum statistics; (5) studying the accuracy with which cluster velocities and momenta may be extracted from observations in different wave bands; and (6) cluster peculiar velocities and momenta from the ACT experiment. This newly accessible source of cosmological information is a novel probe of the formation of structure in the Universe, providing independent tests of the standard model in cosmology and better determining several fundamental parameters.The project includes educational initiatives at a range of levels, including mentoring of a graduate student; involving undergraduates in the research effort; and secondary education and public outreach efforts in cooperation with the Allegheny Observatory.