Mapping the Primordial Universe in Unprecedented Detail with POLARBEAR

Darcy Barron被授予美国国家科学基金会天文学和天体物理学博士后奖学金，在加州大学伯克利分校开展研究和教育项目。巴伦将致力于扩大美国国家科学基金会资助的“北极星熊”项目，该项目是从智利阿塔卡马沙漠的地点绘制宇宙微波背景（CMB）。CMB是来自我们原始宇宙的第一束光，由大爆炸产生的热光产生。对CMB的测量对我们目前对宇宙形成的理解至关重要，但对其极化特性的详细测量仍有更多的发现。CMB领域已经达到了一个重要的里程碑，包括POLARBEAR在内的几个实验，探测到由引力扭曲引起的独特偏振模式。这个信号是如此微弱，以至于这些探测需要对一小片天空进行长达数年的“曝光”。绘制这种信号在天空中的详细地图，将使我们对宇宙结构及其起源的理解取得重大进展。除了这项工作，巴伦还将开展一个外展项目，重点培养高中和社区大学生的基本研究技能和对STEM的兴趣。“北极星熊”项目正在从一个单一波长的望远镜扩展到三个3.5米的望远镜阵列，这些望远镜配备了更大、更宽带宽的相机。这一扩展将使人们能够在三种不同波长下对65%的天空中的微波偏振进行详细的调查。巴伦将专注于新相机的开发和观测，该相机将对CMB的峰值波长和较短的波长都很敏感，在较短的波长中，银河系的发射可能会淹没CMB信号。这些同步测量将用于监测调查区域的银河污染，以便提取潜在的原始CMB极化信号。在部署到智利站点之前，该摄像机将在加州大学伯克利分校进行开发和表征。这些微波望远镜的相机包括复杂的低温和电子系统，读取大量敏感的超导探测器，保持在0.25开尔文的温度。参与外展计划的学生将通过自主射电天文学项目获得软件和硬件开发的实践经验，应用与开发POLARBEAR相机相同的基础知识。

Darcy Barron is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the University of California, Berkeley. Barron will work on the expansion of the NSF-funded POLARBEAR project, which is mapping the cosmic microwave background (CMB) from its site in the Atacama desert in Chile. The CMB is the first light from our primordial universe, generated by the thermal glow from the Big Bang. Measurements of the CMB have been essential to our current understanding of the universe's formation, but there is still more to discover with detailed measurements of its polarization properties. The CMB field has reached an important milestone with several experiments, including POLARBEAR, making detections of a unique polarization pattern resulting from gravitational distortions. This signal is so faint that these detections required years-long "exposures" of a small patch of sky. Making detailed maps of this signal across the sky will enable significant advances in our understanding of the structure of our universe and its origins. Alongside this work, Barron will run an outreach program focused on cultivating basic research skills and interest in STEM with high school and community college students. The POLARBEAR project is expanding from one telescope observing at a single wavelength, to an array of three 3.5 meter telescopes with larger, broader bandwidth cameras. This expansion will enable a detailed survey of microwave polarization across 65% of the sky, at three different wavelengths. Barron will focus on development and observations with the new camera that will be sensitive to both the peak CMB wavelength and a shorter wavelength where Galactic emission can overwhelm the CMB signal. These simultaneous measurements will be used to monitor the Galactic contamination in the survey areas, so that the underlying primordial CMB polarization signal can be extracted. This camera will be developed and characterized at UC Berkeley before being deployed to the Chilean site. The cameras for these microwave telescopes involve complex cryogenic and electronic systems, reading out large numbers of sensitive superconducting detectors, kept at a temperature of 0.25 Kelvin. Students in the outreach program will get hands-on experience with software and hardware development through self-directed radio astronomy projects, applying the same fundamentals that go into the development of the POLARBEAR cameras.