Collaborative Research with the Atacama Cosmology Telescope (ACT): Probing Fundamental Physics Through Observations of Cosmic Structure

最近在观测和理论宇宙学方面令人兴奋的发现使我们得以一窥新的基础物理学。与五年前相比，我们对宇宙的内容和命运的认识更加清晰，也有了巨大的不同。我们现在相信宇宙在几何上是平坦的，由5%的重子、30%的暗物质和65%的一种新形式的暗能量组成。通过高度联锁的观察、复杂的数据分析和理论，参与这项合作项目的研究人员希望扩展我们的知识，远远超出当前一代调查的能力。探测器技术的革命，即千元素辐射热计阵列，为物理宇宙的新发现打开了大门。这个小组将把一个基于这些实地测试阵列的三色毫米相机与一个专门的、直径6米的望远镜连接起来，该望远镜将位于智利海拔5000米以上的地方。利用这台仪器的观测可以绘制出宇宙结构形成时从高红移（z 1000）线性到低红移（z 5）非线性的结构形成图。10米级望远镜的光谱学和现代x射线卫星的测量将能够确定数百个星系团的红移和质量，这是宇宙演化的最新阶段。通过综合观察——宇宙微波背景（CMB）、光学、x射线——研究人员将探测到比以往更深的宇宙图景。阿塔卡马宇宙望远镜（ACT）项目的目标是：绘制超过100平方度的CMB温度各向异性图，超出WMAP（运行）和Planck（2007年发射）卫星的分辨率限制。初级各向异性限制了婴儿期宇宙的基本物理性质，并为结构形成提供了初始条件；次生各向异性反映了结构的出现。2. 通过Sunyaev-Zel'dovich效应寻找和研究CMB地图区域的星系团，并确定其中400多个星系团的光谱红移。这些星团的质量将通过x射线观测和星系速度色散来测量。3. 结合高保真度的CMB地图数据和聚类测量，找到状态方程，w = p/p的“精华”或“暗能量”到+0.1。4. 限制或确定中微子的质量为+0.1 eV从综合的宇宙微波背景图和星团测量。5. 利用宇宙微波背景图构建0.2度分辨率的引力透镜位移图，这将直接探测z ~ 1到2的1 Mpc长度尺度上的总质量分布。这项技术独立于低红移星系调查，并与之互补。6. 通过CMB中的Ostriker-Vishniac效应，探测从z ~ 10的第一批恒星形成的宇宙再电离。该研究小组将结合ACT项目开展一系列教育、外联和技术转让活动。一个特别值得注意的项目是为纽约城市大学的少数族裔学生提供研究经验。本科生和研究生以及博士后将通过参与ACT项目的各个方面接受提前培训。宇宙学研究抓住了公众的想象力，这个项目的结果预计会引起媒体的广泛关注。在NSF内部，ACT项目的资助伙伴是天文科学部、物理部和数学与物理科学理事会的多学科活动办公室。* * *

AST-0408698PageExciting recent discoveries in observational and theoretical cosmology have given us a glimpse of new fundamental physics. Our conception of the contents and fate of the Universe is clearer and dramatically different than it was just five years ago. We now believe the Universe is geometrically flat and comprised of ~5% baryons, ~30% dark matter, and ~65% a new form of dark energy. Through a highly interlocking program of observations, sophisticated data analysis, and theory, the researchers involved in this collaborative project expect to expand our knowledge well beyond the capabilities of the current generation of investigations. A revolution in detector technology, namely thousand-element bolometric arrays, has opened the door to new discoveries about the physical Universe. This group will couple a three-color millimeter camera based on these field-tested arrays to a specialized, 6-meter diameter telescope to be located at an altitude above 5000 m in Chile. Observations with this instrument can map out the formation of cosmic structure from the high-redshift (z 1000) linear regime through the low-redshift (z 5) non-linear regime when structures form. Optical spectroscopy with 10-meter class telescopes and measurements with modern X-ray satellites will enable the determination of the redshifts and masses of hundreds of galaxy clusters, the latest stage of cosmic evolution. Through a combination of observations - Cosmic Micowave Background (CMB), optical, X-ray - the researchers will probe the picture of the Universe to greater depths than have yet been plumbed. Goals of the Atacama Cosmology Telescope (ACT) project are to: 1. Map the CMB temperature anisotropy over 100 square deg, beyond the resolution limits of the WMAP (operating) and Planck (launch 2007) satellites. The primary anisotropy constrains the fundamental physics of the infant Universe and provides the initial conditions for structure formation; the secondary anisotropies reflect the emergence of structure. 2. Find and study galaxy clusters in the CMB map region through the Sunyaev-Zel'dovich effect and determine the spectroscopic redshifts of over 400 of them. The masses of these clusters will be measured with X-ray observations and with galaxy velocity dispersions. 3. Combine the high fidelity CMB map data and the cluster measurements to find the equation of state, w = p/p of the "quintessence" or "dark energy" to +0.1. 4. Limit or determine the mass of the neutrino to +0.1 eV from the combined CMB map and cluster measurements. 5. Use the CMB maps to construct gravitational lensing displacement maps at 0.2 degree resolution, which will probe the total mass distribution directly on length scales of 1 Mpc at z ~ 1 to 2. This technique is independent of and complementary to lower redshift galaxy surveys (which involve bias). 6. Detect reionization of the Universe from the formation of the first stars at z ~ 10 through the Ostriker-Vishniac effect in the CMB.This research team will conduct a range of activities in education, outreach, and technology transfer in conjunction with the ACT project. One program of special note gives research experience to minority students at City University of New York. Undergraduate and graduate students as well as postdocs will receive advance training through participation in all aspects of the ACT project. Cosmology research captures the public imagination, and the results of this project are expected to generate considerable media attention. Within NSF, the funding partners for the ACT project are the Division of Astronomical Sciences, the Division of Physics, and the Office of Multidisciplinary Activities in the Directorate for Mathematical and Physical Sciences. ***