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诞生于大爆炸后数亿年。这些恒星与今天存在的任何恒星都不同，这段被称为“宇宙黎明”的宇宙历史在很大程度上是未知的领域。通过对天空的无线电频率测量，可以观测到这些第一批恒星。氢是宇宙中最丰富的元素，自然会发出波长为21厘米的光。因为宇宙在膨胀，所以这个波长会随着氢原子发出光的距离（或者说，是多久以前）成比例地被拉长。氢的射电辐射敏感地依赖于第一颗恒星，因此是阐明其物理性质和形成历史的有力工具。然而，在这些频率（<200 MHz）的观测是非常困难的，因为来自天空的信号很容易被仪器行为的不确定性所污染。特别是，接收入射光的天线以微妙的方式受到地下地球电磁特性的影响：从本质上讲，地面是仪器的组成部分，因此必须作为实验的一部分进行表征。该提案将支持一个探地雷达系统，该系统将用于对土壤电磁特性进行高精度测量，以供宇宙黎明实验使用。宇宙黎明仪器已经在麦吉尔开发，子系统已经广泛的特点。我们将从麦吉尔北极研究站和魁北克中部的Uapishka站进行观察，我们的团队已将其确定为代表加拿大独特地理优势的杰出无线电安静站点。有了新的宇宙黎明仪器，以及一流的观测位置，GPR将为宇宙黎明测量带来新的精度水平，并将有助于打开无线电天空的新窗口。