Ground-penetrating radar for precision radio cosmology

用于精确射电宇宙学的探地雷达

• 批准号: RTI-2022-00115
• 负责人: Chiang, Hsin
• 金额: $ 4.14万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742923
• 关键词: Ground; penetrating; radar; precision; radio

The first stars in the universe were born a few hundred million years after the big bang. These stars were unlike any that exist today, and this period of the universe's history, known as "cosmic dawn," is largely uncharted territory. Observations of these first stars are possible via radio-frequency measurements of the sky. Hydrogen, which is the most abundant element in the universe, naturally emits light with a wavelength of 21 cm. Because the universe is expanding, this wavelength is stretched in proportion to how far away (or, equivalently, how long ago) the hydrogen emitted its light. The radio emission from hydrogen depends sensitively upon the first stars and is therefore a powerful tool for elucidating their physical properties and formation history. However, observations at these frequencies (<200 MHz) are exceptionally difficult because the signal from the sky can be easily contaminated by uncertainties in the instrument behavior. In particular, the antenna that receives incoming light is influenced in subtle ways by the electromagnetic properties of the underlying earth: in essence, the ground is an integral part of the instrument and therefore must be characterized as part of the experiment. This proposal will support a ground-penetrating radar (GPR) system that will be used to perform high-precision measurements of soil electromagnetic properties for cosmic dawn experiments. The cosmic dawn instrumentation has already been developed at McGill, and the subsystems have been extensively characterized. We will observe from the McGill Arctic Research Station and Uapishka Station in central Quebec, which our team has identified as outstanding radio-quiet sites that represent a unique Canadian geographic advantage. With novel cosmic dawn instrumentation in hand, as well as superb observing locations, the GPR will bring a new level of precision to cosmic dawn measurements and will help open a new window on the radio sky.

宇宙中的第一批恒星是在大爆炸后几亿年诞生的。这些恒星与当今存在的任何恒星都不同，宇宙历史的这段时期（被称为“宇宙黎明”）在很大程度上是未知的领域。通过天空的射频测量可以观测到这些第一颗恒星。氢是宇宙中最丰富的元素，自然发射波长为 21 厘米的光。因为宇宙正在膨胀，所以这个波长与氢发出光的距离（或者等效地，多久前）成比例地拉伸。氢的无线电发射敏感地取决于第一批恒星，因此是阐明其物理特性和形成历史的有力工具。然而，在这些频率（<200 MHz）下进行观测非常困难，因为来自天空的信号很容易受到仪器行为的不确定性的污染。特别是，接收入射光的天线会受到地下地球电磁特性的微妙影响：本质上，地面是仪器的一个组成部分，因此必须将其作为实验的一部分进行表征。该提案将支持探地雷达（GPR）系统，该系统将用于对宇宙黎明实验的土壤电磁特性进行高精度测量。麦吉尔已经开发出宇宙黎明仪器，并且已经对子系统进行了广泛的表征。我们将从麦吉尔北极研究站和魁北克中部的乌皮什卡站进行观察，我们的团队已将其确定为出色的无线电安静站点，代表了加拿大独特的地理优势。凭借新颖的宇宙黎明仪器以及一流的观测地点，探地雷达将为宇宙黎明测量带来新的精度水平，并有助于打开射电天空的新窗口。