Precision Beam Mapping for 21cm Cosmology

21cm 宇宙学的精密光束映射

• 批准号: 1711179
• 负责人: Daniel Jacobs
• 金额: $ 33.91万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1711179&HistoricalAwards=false
• 关键词: Precision; Beam; Mapping; 21cm; Cosmology

Understanding the epoch of early galaxy formation is a key objective of astronomy in the coming decade. This distant, early phase of the Universe is revealed by radio-wave emissions from hydrogen atoms. Detecting such emission is the goal of radio interferometer arrays. This project is an innovative method of calibrating one such experiment. Jacobs and collaborators will use a remote controlled drone octocopter to fly a calibration source over the array and directly measure its response. Preliminary results demonstrate that this approach is superior to more established methods. However, drone calibration has not yet been proven for entire arrays. This project is notable for student participation and the popularity that drone flights achieve in the public imagination. It will set a new and inexpensive standard for array calibration. This use of drones captivates students and the general public at outreach events and sets an example of the careful, methodical process of scientific investigation.This project supports the broad objective of understanding early galaxy formation by detecting redshifted 21cm hydrogen emission using radio telescope arrays. The Hydrogen Epoch of Reionization Array (HERA), supported by NSF in the Mid-Scale Innovations Program, is one such initiative. This project seeks to directly map the primary beams of HERA using a calibrated transmitter mounted to a computer controlled drone octocopter. Drone-based calibration of radio telescopes is gaining popularity, but the method is still experimental. This project is an outgrowth of a previous, successful award that demonstrated drone-based beam mapping at the Green Bank Observatory. Results of that work demonstrated comparable accuracy and superior beam coverage to other calibration methods. This project will extend the methodology previously done on a single antenna to an entire array.

了解早期星系形成的时代是未来十年天文学的一个关键目标。这个遥远的宇宙早期阶段是由氢原子发射的无线电波揭示的。探测这种发射是无线电干涉仪阵列的目标。这个项目是校准这样一个实验的创新方法。雅各布斯和他的合作者将使用一架遥控无人机在阵列上空飞行一个校准源，并直接测量其响应。初步结果表明，该方法优于现有的方法。然而，无人机校准尚未被证明适用于整个阵列。这个项目值得注意的是学生的参与和无人机飞行在公众想象中的普及。它将为阵列校准设定一个新的廉价标准。这种无人机的使用吸引了学生和公众参加外展活动，并为科学调查的仔细、系统过程树立了榜样。该项目支持通过使用射电望远镜阵列探测红移21cm氢发射来了解早期星系形成的广泛目标。由美国国家科学基金会在中等规模创新计划中支持的氢再电离阵列（HERA）就是这样一个倡议。该项目旨在使用安装在计算机控制的无人机上的校准发射器直接绘制HERA的主波束。基于无人机的射电望远镜校准越来越受欢迎，但这种方法仍处于实验阶段。该项目是之前一个成功的奖项的产物，该奖项在绿岸天文台展示了基于无人机的光束测绘。该工作的结果表明，与其他校准方法相比，该方法具有相当的精度和优越的波束覆盖范围。该项目将把以前在单个天线上完成的方法扩展到整个阵列。

项目成果

First Demonstration of ECHO: an External Calibrator for Hydrogen Observatories

• DOI: 10.1088/1538-3873/aa56b9
• 发表时间: 2017-02
• 期刊: Publications of the Astronomical Society of the Pacific
• 影响因子: 3.5
• 作者: D. Jacobs;Jacob Burba;J. Bowman;A. Neben;Benjamin Stinnett;Lauren Turner;Kali Johnson;M. Busch;Jay Allison;M. Leatham;Victoria Serrano Rodriguez;Mason Denney;David Nelson