EDGES-2: Detecting First Light and Reionization through the Global 21 cm Signature

EDGES-2：通过全局 21 厘米特征检测第一光和再电离

• 批准号: 1207761
• 负责人: Judd Bowman
• 金额: $ 84.21万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207761&HistoricalAwards=false
• 关键词: EDGES; Detecting; First; Light; Reionization

The formation of the first stars, galaxies, and black holes during what is known as the Cosmic Dawn is the next frontier in observational cosmology. During this epoch, the intergalactic medium (IGM) was primarily in the form of neutral hydrogen gas, accessible to observations through its redshifted 21 cm line. Once the first stars formed at a redshift z ~ 30, they produced a background of Lyman-alpha photons that coupled the neutral hydrogen spin temperature to the physical gas temperature in the IGM. This is thought to have caused the 21 cm line to become visible in absorption against the cosmic microwave background (CMB). Later, X-rays traveling long distances deposited their energy as heat and raised the IGM temperature. This heating drove the average 21 cm signal to rise into emission above the CMB, until the neutral gas was eventually ionized during the epoch of reionization, and no detectable signal remained. The evolution of these absorption and emission features in the early IGM should be evident in cosmic radio spectrum, since redshift maps to frequency for the 21 cm line. Significant observational challenges must be addressed to separate the expected 10-100 mK high-redshift 21 cm signal from the dominant Galactic foreground emission, but Dr. Judd Bowman of the Arizona State University and his collaborators at the Massachusetts Institute of Technology propose to overcome these challenges with a spectrometer featuring 10 times improved performance and frequency coverage from 40 to 200 MHz to span the redshift range 6 z 30. The new instrument, called EDGES-2, will make use of a new precision calibration method based on a generalization of the classic noise wave propagation model. Broader impacts of the project include demonstration of this new, high-precision calibration method for wideband systems, which has applications outside of radio astronomy, including to ionospheric study. The project also has a strong focus on providing opportunities for undergraduate and graduate student training and mentoring in an interdisciplinary environment to learn basic principles of digital signal processing, software design, statistical analysis, model fitting, and astrophysics. Funding for the development of the EDGES-2 project is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.

在所谓的宇宙黎明期间，第一批恒星，星系和黑洞的形成是观察宇宙学的下一个前沿。 在这个时期期间，层间培养基（IgM）主要采用中性氢气的形式，可以通过其红移21 cm线观测到观测。 一旦第一颗恒星在红移Z〜30形成，它们就产生了Lyman-Alpha光子的背景，该恒星将中性氢自旋温度与IgM中的物理气体温度耦合。人们认为这导致21 cm线在吸收宇宙微波背景（CMB）方面变得可见。 后来，X射线长距离将其能量沉积在热量并提高IGM温度时。这种加热使平均21 cm的信号升​​至CMB上方的发射，直到最终在电离时期内中性气体电离，并且没有可检测的信号。这些吸收和发射特征在早期IgM中的演变应在宇宙无线电谱中显而易见，因为红移映射到21 cm线的频率。 Significant observational challenges must be addressed to separate the expected 10-100 mK high-redshift 21 cm signal from the dominant Galactic foreground emission, but Dr. Judd Bowman of the Arizona State University and his collaborators at the Massachusetts Institute of Technology propose to overcome these challenges with a spectrometer featuring 10 times improved performance and frequency coverage from 40 to 200 MHz to span the redshift range 6 z 30. The new instrument, called Edges-2将基于经典噪声波传播模型的概括来利用一种新的精确校准方法。 该项目的更广泛的影响包括针对宽带系统的这种新的高精度校准方法的演示，该方法在射电天文学之外具有应用，包括电离层研究。该项目还非常重视在跨学科环境中为本科和研究生培训和指导提供机会，以学习数字信号处理，软件设计，统计分析，模型拟合和天体物理学的基本原理。 NSF的天文科学部通过其先进的技术和仪器计划提供了为Edges-2项目开发的资金。