Large Angular Scale Polarization Survey of the Cosmic Microwave Background - Phase Two

宇宙微波背景大角尺度偏振测量 - 第二阶段

• 批准号: 2034400
• 负责人: Charles Bennett
• 金额: $ 359.37万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-15 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2034400&HistoricalAwards=false
• 关键词: Large; Angular; Scale; Polarization; Survey

This award supports new observations with the Cosmology Large Angular Scale Surveyor (CLASS). The main science goals of CLASS are (1) to measure when the first stars lit up the universe and (2) to detect and characterize primordial gravitational waves created at the start of the universe. The first goal is important for understanding how galaxies formed and also improves our ability to measure the mass of fundamental particles called neutrinos, the study of which is a frontier in physics. The second goal will tell us what happened at the earliest moments of the universe and connects gravity with quantum mechanics, a long-term quest in physics. To accomplish these goals, telescopes with new technologies have been developed over the past decade and deployed high in the Chilean Andes, in the Atacama Desert. This is a premier site for observations of the Cosmic Microwave Background (CMB), which is the afterglow of the hot early universe. CLASS probes the largest-angular-scale (more than 10 degrees across the sky) variations in the CMB polarization to reach its science goals. Broader societal impacts include rigorous training of students and postdocs in the US and Chile. CLASS reaches the public through public events at universities and local schools, Quarknet high-school teacher training, and development of high-school-level cosmology modules. Publications and data will be publicly distributed. Transformational data on the early universe will be of enormous interest to physicists, astronomers, students, and the general public.CLASS is unique among current CMB surveys in targeting CMB polarization corresponding to angular multipoles down to ell of order 2. At these scales, scattering of CMB photons by the ionized intergalactic medium (post reionization) alters the CMB polarization angular spectra (both E and B-modes). This distinctive low-ell signature in the angular power spectrum is targeted by CLASS to measure the optical depth to reionization at the cosmic-variance limit and the tensor-to-scalar ratio at the 0.01 level. CLASS uses four telescopes to measure the CMB polarization over 70% of the sky. The telescope array observes at four microwave frequencies (40, 90, 150, and 220 GHz) to differentiate between the CMB signal and the microwave emission from our Galaxy. The key technology enabling the low-ell measurement through low-frequency noise reduction is rapid polarization amplitude modulation with a Variable-delay Polarization Modulator. Additional technology developments include novel microwave optics, cryogenic transition-edge sensors, and a custom high-performance data pipeline. The initial 5-year CLASS survey (funded under a previous MSIP), was begun in 2016. This grant allows the team to capitalize on developments in instrumentation, survey strategy, and data analysis pipeline from the first five years, and acts as a bridge to future, enhanced measurements.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项支持宇宙学大角尺度测量仪（CLASS）的新观测。 CLASS 的主要科学目标是 (1) 测量第一颗恒星何时点亮宇宙；(2) 探测和表征宇宙诞生时产生的原始引力波。第一个目标对于理解星系如何形成非常重要，并且还提高了我们测量称为中微子的基本粒子质量的能力，中微子的研究是物理学的前沿。第二个目标将告诉我们宇宙最初时刻发生了什么，并将引力与量子力学联系起来，这是物理学的长期探索。为了实现这些目标，在过去十年中开发了采用新技术的望远镜，并将其部署在智利安第斯山脉阿塔卡马沙漠的高处。这是观测宇宙微波背景（CMB）的首要地点，宇宙微波背景是炎热的早期宇宙的余辉。 CLASS 探测 CMB 偏振的最大角尺度（超过天空 10 度）变化，以实现其科学目标。更广泛的社会影响包括对美国和智利的学生和博士后的严格培训。 CLASS 通过大学和当地学校的公共活动、Quarknet 高中教师培训以及高中水平宇宙学模块的开发来接触公众。出版物和数据将公开分发。早期宇宙的转变数据将引起物理学家、天文学家、学生和公众的极大兴趣。CLASS 在当前的 CMB 巡天中是独一无二的，其目标是对应于低至 2 阶角多极子的 CMB 偏振。在这些尺度上，散射电离星际介质（再电离后）产生的 CMB 光子改变了 CMB 偏振角光谱（E 模式和 B 模式）。 CLASS 的目标是角功率谱中这种独特的低阱特征，以测量宇宙方差极限下的再电离光学深度和 0.01 水平的张量标量比。 CLASS 使用四台望远镜来测量 70% 天空的 CMB 偏振。望远镜阵列以四种微波频率（40、90、150 和 220 GHz）进行观测，以区分 CMB 信号和来自银河系的微波发射。通过低频降噪实现低增益测量的关键技术是使用可变延迟偏振调制器进行快速偏振幅度调制。其他技术开发包括新颖的微波光学器件、低温过渡边缘传感器和定制的高性能数据管道。最初的 5 年 CLASS 调查（由之前的 MSIP 资助）于 2016 年开始。这笔赠款使团队能够利用前五年在仪器、调查策略和数据分析管道方面的发展，并充当桥梁该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Long-timescale stability in CMB observations at multiple frequencies using front-end polarization modulation

使用前端偏振调制在多个频率下实现 CMB 观测的长时标稳定性

• DOI: 10.1117/12.2629723
• 发表时间: 2022-08
• 期刊: and Far-Infrared Detectors and Instrumentation for Astronomy XI
• 作者: Cleary, Joseph;Datta, Rahul;Appel, John;Bennet, Charles;Chuss, David;Denes Couto, Julliana;Dahal, Sumit;Espinoza, Francisco;Essinger;Harrington, Kathleen;et al
• 通讯作者: et al

Cosmology Large Angular Scale Surveyor (CLASS): pointing stability and beam measurements at 90, 150, and 220 GHz

宇宙学大角尺度测量仪 (CLASS)：90、150 和 220 GHz 的指向稳定性和波束测量

• DOI: 10.1117/12.2630649
• 发表时间: 2022-08
• 期刊: and Far-Infrared Detectors and Instrumentation for Astronomy XI
• 作者: Datta, Rahul;Brewer, Michael K.;Denes Couto, Jullianna D.;Eimer, Joseph R.;Li, Yunyang;Xu, Zhilei;Appel, John W.;Bustos, Ricardo;Chuss, David;Cleary, Joseph;et al
• 通讯作者: et al

Testing Cosmic Microwave Background Anomalies in E-mode Polarization with Current and Future Data

用当前和未来的数据测试 E 模式偏振中的宇宙微波背景异常

• DOI: 10.3847/1538-4357/acb339
• 发表时间: 2023-03
• 期刊: The Astrophysical Journal
• 作者: Shi 时, Rui 瑞.;Marriage, Tobias A.;Appel, John W.;Bennett, Charles L.;Chuss, David T.;Cleary, Joseph;Eimer, Joseph R.;Dahal सुिमत, Sumit दाहाल;Datta, Rahul;Espinoza, Francisco;et al
• 通讯作者: et al

Venus Observations at 40 and 90 GHz with CLASS

使用 CLASS 在 40 和 90 GHz 进行金星观测

• DOI: 10.3847/psj/abedad
• 发表时间: 2021-04
• 期刊: The Planetary Science Journal
• 作者: Dahal, Sumit;Brewer, Michael K.;Appel, John W.;Ali, Aamir;Bennett, Charles L.;Bustos, Ricardo;Chan, Manwei;Chuss, David T.;Cleary, Joseph;Couto, Jullianna D.;et al
• 通讯作者: et al

Design and characterization of new 90 GHz detectors for the Cosmology Large Angular Scale Surveyor (CLASS)

用于宇宙学大角尺度测量仪 (CLASS) 的新型 90 GHz 探测器的设计和表征

• DOI: 10.1117/12.2630081
• 发表时间: 2022-08
• 期刊: and Far-Infrared Detectors and Instrumentation for Astronomy XI
• 作者: Nunez, Carolina;Appel, John W.;Bruno, Sarah Marie;Datta, Rahul;Ali, Aamir;Bennett, Charles L.;Dahal, Sumit;Denes Couto, Jullianna;Denis, Kevin;Eimer, Joseph;et al
• 通讯作者: et al