A Precision Measurement of the Polarization of the 2.7K Cosmic Microwave Background Radiation

2.7K宇宙微波背景辐射偏振的精确测量

• 批准号: 9318727
• 负责人: Peter Timbie
• 金额: $ 23.96万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-06-01 至 1997-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9318727&HistoricalAwards=false
• 关键词: Precision; Measurement; Polarization; 2.7K; Cosmic

ABSTRACT 9318727 Timbie Recent measurements of the spectrum and the spatial anisotropy of the 2.7K Cosmic Microwave Background Radiation (CMBR) have dramatically improved our understanding of the early universe. The third characteristic of this radiation, its polarization, has not been measured as precisely. The amplitude of the linear polarization and its angular coherence length are extremely sensitive to both the source of anisotropy (density perturbations or gravitational waves) and the ionization history of the universe. The predicted polarization amplitude is 10% of the size of the COBE/DMR anisotropy signals at 7, or T/T110-6. This grant will support o perform the first measurements optimized for this angular scale and smaller. It will use new receiver technology with 100 times more sensitivity than previous polarization experiments, as well as a novel instrument design. It is expected to reach a factor of about 100 below present upper limits at this scale. An improved upper limit, or detection of polarization will help to: determine whether the large-scale anisotrophies were generated by density perturbations or by gravitational waves determine if recombination was instantaneous determine the redshift of reionization study the correlation of anisotropy with polarization constrain possible alternative sources of polarization of the CMBR such as axions, cosmic strings, and textures The project will measure CMBR polarization, first at large angular scales (7) and later at smaller scales (1). Two novel polarimeters optimized specifically for both measurements are being constructed. They will operate at two different millimeter wavelengths to reject foreground emission from synchrotron radiation and feature strictly- controlled systematic effects and the high sensitivity required to reach the expected signal level. ***

摘要 小行星9318727 最近对2.7K宇宙微波背景辐射（CMBR）的光谱和空间各向异性的测量极大地提高了我们对早期宇宙的理解。 这种辐射的第三个特性，即它的偏振，还没有被精确地测量过。 线偏振的振幅和它的角相干长度对各向异性的来源（密度扰动或引力波）和宇宙的电离历史都非常敏感。 预测的偏振振幅是7或T/T110-6处COBE/DMR各向异性信号大小的10%。 该授权将支持执行针对该角度标度和更小的角度标度优化的第一测量。 它将使用新的接收器技术，其灵敏度比以前的偏振实验高100倍，以及新颖的仪器设计。 预计在这个比额表上，它将比目前的上限低约100倍。 改进的上限或偏振检测将有助于： 确定大规模的各向异性是否 由密度扰动或引力 波 确定重组是否是瞬时的 测定再电离的红移 研究各向异性与极化的相关性 限制可能的极化替代来源， CMBR，如轴子、宇宙弦和纹理 该项目将首先在大角度尺度（7）上测量CMBR偏振，然后在较小的尺度（1）上测量。 两个新的偏振仪专门为这两种测量优化正在建设中。 它们将在两个不同的毫米波长下工作，以拒绝来自同步辐射的前景发射，并具有严格控制的系统效应和达到预期信号水平所需的高灵敏度。 ***