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）项目旨在探测宇宙大爆炸后约1亿年（红移16-40）星系际介质中中性氢（静止波长21厘米）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将开发和集成信号处理仪器到长波阵列（LWA）的新第一站。这包括一个大n相关器，服务于LWA-1的所有512个偶极天线，利用分组CASPER架构，并为F级和X级结合fpga和gpu。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）中绘制，该库专门用于支持具有固定偶极子阵列的宽视场全偏振成像。校准技术将包括校正电离层折射和方向相关的偶极子增益，以及探索脉冲星数据分析以提高性能。精确的校准和成像将是LEDA的关键要求，这对于减去明亮的前景天空和探测微弱的中性氢信号是必要的。从计算的角度来看，LEDA是一个每秒0（100）万亿次浮点运算的挑战，它使可扩展的架构能够面向无线电阵列的发展，需要每秒10万亿次浮点运算的节能性能。氢再电离阵列（HERA2）的第二阶段就是一个例子。第一批恒星是什么时候形成的？这些恒星预计会比我们周围的恒星大得多。超大质量黑洞是同时形成的，是更早还是更晚？当今宇宙学最大的挑战之一就是对这些第一代天体的研究。人们普遍假设它们的形成始于大爆炸后大约1亿年，但没有可用的数据来验证这一理论。要研究如此年轻的宇宙（只有今天的1%），唯一可行的方法是通过恒星和黑洞之间星系间介质的电磁辐射。今天，它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储存库，为第一批恒星和黑洞的形成提供了燃料，并辐射出大量的长波辐射。LEDA项目寻求应用前沿射电天文学技术来首次探测到这种信号。LEDA将建造一个“射电摄像机”，用于部署在新墨西哥州的长波阵射电望远镜上，长波阵射电望远镜的第一个直径100米的孔径最近刚刚完成。LEDA相机将结合几种创新技术和数据分析技术，为学生和年轻科学家提供加入尖端科学和开发最先进工具的机会。特别是，LEDA将利用巨大的计算能力和图形处理单元（gpu）的灵活性-为视频游戏提供动力的引擎-制作几乎整个天空的瞬时图像，波长高达10米（比可见辐射长1000万倍）。从这些图像中，我们和其他星系的光将被高精度地减去，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，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是关键。LEDA项目的跨学科成果将有利于天文学、计算科学和太阳科学。