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

Ruhl博士和Timbie博士正在合作进行一项分两阶段的计划来测量宇宙微波背景（CMB），首先在大角度尺度上，然后在小尺度上。该程序在单个毫米频带（26- 36ghz）中运行。最近对2.7K CMB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征，即它的极化，还没有被探测到。线极化的振幅及其空间分布对温度各向异性的来源（密度扰动或引力波）和宇宙的电离历史都极为敏感。预测的极化幅度小于或等于COBE（宇宙微波背景探测器）各向异性信号在70度的10%。研究小组正在使用比以前的偏振实验灵敏度提高100倍的新接收器技术，以及一种新的仪器设计。对偏振的探测将有助于：提供宇宙结构形成的细节；补充宇宙参数的CMB温度各向异性测量；确定复合是否瞬间发生；确定再电离红移；区分结构形成的膨胀模型和缺陷模型；探测早期宇宙和星系团中的磁场；了解银河系和银河系外的极化辐射源。＊＊＊

AST-9813920 John Ruhl Dr. Ruhl and Dr. Timbie are collaborating on a two-phase program to measure the cosmic microwave background (CMB), first at large angular scales and later at small scales. This program operates in a single millimeter frequency band (26-36 GHz). .Recent measurements of the spectrum and the spatial anisotropy of the 2.7K CMB have dramatically improved our understanding of the early universe. The third characteristic of this radiation, its polarization, has not yet been detected. The amplitude of the linear polarization and its spatial distribution are extremely sensitive to both the source of the temperature anisotropy (density perturbations or gravitational waves) and the ionization history of the universe. The predicted polarization amplitude is less than or equal to 10% of the size of the COBE (Cosmic Microwave Background Explorer) anisotropy signals at 7o. The research team is using new receiver technology with 100 times more sensitivity than previous polarization experiments, as well as a novel instrument design. Detection of polarization will help to: provide details about the formation of structure in the universe; complement CMB temperature anisotropy measurements of cosmological parameters; determine if recombination was instantaneous; determine the redshift of reionization; distinguish between inflation and defect models for structure formation; probe magnetic fields in the early universe and in clusters of galaxies; understand galactic and extragalactic sources of polarized radiation. ***