Probing the Cosmic Dawn and Epoch of Re-ionization with the REACH experiment

通过 REACH 实验探索宇宙黎明和再电离时代

• 批准号: EP/Y02916X/1
• 负责人: Eloy De Lera Acedo
• 金额: $ 300.94万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FY02916X%2F1
• 关键词: Probing; Cosmic; Dawn; Epoch; Re

How did the Universe transition from a mostly empty volume after the Big Bang to a complex realm of stars, galaxies and other celestial objects? This unknown process occurred during the so-called Cosmic Dawn and the Epoch-of-Reionziation. 21-cm radio-cosmology is the field of research promising to unlock the secrets of the infant Universe by studying radio signals from the most abundant element in the Universe: hydrogen. I request funding to assemble a research team to focus on the detection and study of the elusive 21-cm signal from atomic hydrogen using the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH) that I conceived and lead. Radio-interferometers have already placed upper limits on the 21-cm power spectra, while it is the single-antenna experiments, measuring the 21-cm signal averaged across all directions in the sky, the ones that are promising even earlier breakthroughs. The EDGES experiment shook the field in 2018 reporting a cosmological signal twice deeper than expected requiring exotic physics to be explained. This has been contested by several groups amid concerns on the data analysis and potential impact of hardware systematic signals, including recent measurements from the SARAS3 experiment incompatible with the EDGES findings. The contamination from instru- ment systematics is the main bottleneck for "1st generation" 21-cm radio telescopes. Aiming to resolve these concerns, a new experimental approach has emerged over the last 5 years giving birth to a 2nd generation of experiments. REACH is a sky-averaged experiment leading this new wave of instruments, where the focus has shifted to a data-driven hardware and algorithm design focusing on the detection and isolation of instrumental systematic signals. To this end REACH uses a fully Bayesian data pipeline to jointly fit instrument models with models of the sky sig- nals. During this project I will lead the team aiming at a first confident detection and study of the sky-averaged 21-cm line.

宇宙是如何从大爆炸后几乎空无一物的体积转变为由恒星、星系和其他天体组成的复杂领域的？这个未知的过程发生在所谓的宇宙黎明和再电离时代。 21 厘米射电宇宙学是一个研究领域，有望通过研究来自宇宙中最丰富的元素：氢的无线电信号来解开婴儿宇宙的秘密。我请求资金组建一个研究团队，利用我构思和领导的宇宙氢分析无线电实验 (REACH)，重点检测和研究来自原子氢的难以捉摸的 21 厘米信号。射电干涉仪已经对 21 厘米功率谱设定了上限，而单天线实验测量了天空各个方向的平均 21 厘米信号，这些实验有望更早取得突破。 2018 年，EDGES 实验震惊了整个领域，报告的宇宙学信号比预期深两倍，需要解释奇异的物理现象。由于担心数据分析和硬件系统信号的潜在影响，包括 SARAS3 实验的最新测量结果与 EDGES 的发现不兼容，多个团体对此提出了质疑。仪器系统污染是“第一代”21厘米射电望远镜的主要瓶颈。为了解决这些问题，过去 5 年出现了一种新的实验方法，催生了第二代实验。 REACH 是引领新一波仪器浪潮的一次天平均实验，其重点已转移到数据驱动的硬件和算法设计，重点是仪器系统信号的检测和隔离。为此，REACH 使用完全贝叶斯数据管道将仪器模型与天空信号模型联合拟合。在这个项目中，我将领导团队的目标是首次自信地检测和研究天空平均 21 厘米线。