Collaborative Research: Large-Aperture Experiment to Detect the Dark Age (LEDA)

合作研究：探测黑暗时代的大孔径实验（LEDA）

• 批准号: 1106045
• 负责人: Dan Werthimer
• 金额: $ 61.35万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-15 至 2016-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1106045&HistoricalAwards=false
• 关键词: Collaborative; Research; Large; Aperture; Experiment

Technical AbstractThe Large Aperture Experiment to Detect the Dark Ages (LEDA) project seeks to detect hyperfine emission from neutral Hydrogen (21 cm rest wavelength) in the intergalactic medium about 100 million years after the Big Bang (redshifts 16-40). A detection would deliver the first observational constraints on models of structure formation and on the formation of the first stars and black holes in the Universe. LEDA will develop and integrate signal processing instrumentation into the new first station of the Long Wavelength Array (LWA). This comprises a large-N correlator serving all 512 dipole antennas of the LWA-1, leveraging a packetized CASPER architecture and combining FPGAs and GPUs for the F and X stages. Iterative calibration and imaging will rely on warped snapshot imaging and be drawn from a GPU-enabled library (CUWARP) that is designed specifically to support wide-field full polarization imaging with fixed dipole arrays. Calibration techniques will include correction for ionospheric refraction and direction dependent dipole gains, and exploration of pulsar data analysis to improve performance. Accurate calibration and imaging will be crucial requirements for LEDA, necessary to subtract the bright foreground sky and detect the faint neutral Hydrogen signal. From the computational standpoint, LEDA is a O(100) TeraFlop per second challenge that enables a scalable architecture looking toward development of radio arrays requiring power efficient 10 PetaFlop per second performance. Stage two of the Hydrogen Epoch of Reionization Array (HERA2) is one example.Lay AbstractWhen did the first stars form? These stars are expected to be much more massive than the stars that are around us today. Did supermassive black holes form at the same time, earlier, or later? One of the great challenges of cosmology today is the study of these first generation objects. Their formation is widely hypothesized to have begun about 100 million years after the Big Bang, but no data are available to test this theory. The only available means to study the Universe at so young an age (just 1% of what it is today) is via electromagnetic radiation from the intergalactic medium between the stars and black holes. Today, this is hot and ionized plasma, but in the early Universe it was a vast reservoir of cold neutral Hydrogen gas that fed the formation of the first stars and black holes and radiated long wavelength radiation copiously.The LEDA project seeks to apply frontier radio astronomical techniques to make the first detection of this signal. LEDA will build a "radio camera" for deployment to the Long Wavelength Array, a radio telescope in New Mexico whose first 100m-diameter aperture was recently completed. The LEDA camera will combine several innovative technologies and data analysis techniques, giving students and young scientists the opportunity to join in cutting-edge science and development of the most advanced tools. In particular, LEDA will harness the massive computing power and flexibility of Graphics Processing Units (GPUs) - the engines that power video games - to make instantaneous images of nearly the whole sky at up to 10 meters wavelength (10 million times longer than visible radiation).From these images the light of our and other galaxies will be subtracted with high accuracy, enabling a search for signals from the dawn of the Universe. LEDA will push the frontiers of cosmology while contributing groundwork for future radio astronomical facilities where massive computing and signal processing systems will be lynchpins. Cross-disciplinary outgrowths of the LEDA effort will benefit astronomical, computational and solar sciences.

技术摘要探测黑暗时代的大孔径实验 (LEDA) 项目旨在探测大爆炸（红移 16-40）后约 1 亿年星际介质中中性氢（21 厘米静止波长）的超精细发射。探测将为结构形成模型以及宇宙中第一批恒星和黑洞的形成提供第一个观测约束。 LEDA 将开发信号处理仪器并将其集成到长波长阵列 (LWA) 的新第一站中。这包括一个为 LWA-1 的所有 512 个偶极子天线提供服务的大 N 相关器，利用分组化 CASPER 架构并将 FPGA 和 GPU 结合用于 F 和 X 级。迭代校准和成像将依赖于扭曲快照成像，并从支持 GPU 的库 (CUWARP) 中提取，该库专门设计用于支持固定偶极子阵列的宽视场全偏振成像。校准技术将包括电离层折射和方向相关偶极子增益的校正，以及脉冲星数据分析的探索以提高性能。准确的校准和成像将是 LEDA 的关键要求，这是减去明亮的前景天空并检测微弱的中性氢信号所必需的。从计算的角度来看，LEDA 是每秒 O(100) TeraFlop 的挑战，它支持可扩展的架构，旨在开发需要每秒 10 PetaFlop 性能的高能效无线电阵列。再电离阵列氢纪元 (HERA2) 的第二阶段就是一个例子。 摘要第一颗恒星何时形成？预计这些恒星比我们今天周围的恒星要大得多。超大质量黑洞是同时形成、更早还是更晚形成？当今宇宙学面临的巨大挑战之一是对这些第一代天体的研究。人们普遍假设它们的形成是在大爆炸后约一亿年开始的，但没有可用的数据来检验这一理论。在如此年轻的年龄（仅为当今宇宙的 1%）研究宇宙的唯一可用方法是通过来自恒星和黑洞之间的星系间介质的电磁辐射。今天，这是热的电离等离子体，但在早期的宇宙中，它是一个巨大的冷中性氢气库，为第一批恒星和黑洞的形成提供了能量，并辐射出大量的长波长辐射。LEDA 项目寻求应用前沿无线电天文技术首次探测到了这个信号。 LEDA 将建造一台“射电相机”，部署到新墨西哥州的长波阵列射电望远镜，其第一个 100m 直径孔径最近已完工。 LEDA相机将结合多项创新技术和数据分析技术，为学生和年轻科学家提供参与尖端科学和最先进工具开发的机会。特别是，LEDA 将利用图形处理单元 (GPU)（视频游戏的引擎）的强大计算能力和灵活性，以高达 10 米的波长（比可见辐射长 1000 万倍）拍摄几乎整个天空的即时图像。 ）。将从这些图像中高精度地减去我们和其他星系的光，从而能够搜索来自宇宙黎明的信号。 LEDA 将推动宇宙学的前沿发展，同时为未来的射电天文设施奠定基础，其中大规模计算和信号处理系统将成为关键。 LEDA 的跨学科成果将有利于天文学、计算和太阳科学。