Unlocking the unexplored epoch of cosmic dawn with radio telescopes and advanced analysis techniques

宇宙学家现在既观察了今天的宇宙，也观察了它的原始条件。然而，宇宙黎明的关键时期-第一批恒星和星系照亮我们宇宙的时期-仍然没有被观测到。因此，我们仍然不知道现代天文结构是如何形成的。例如，第一批星系的性质是什么？它们主要是大星系还是更大范围的小星系？中微子和(可能)湮灭暗物质的粒子物理学在这个时代扮演了什么角色？ 我的研究计划开启了宇宙黎明时代的直接观测。我们通过21厘米的断层摄影术做到这一点，中性氢原子发出的微弱射电辐射被用来绘制我们宇宙的大比例地图。然后，这些地图提供了第一代星系如何照亮、电离和永久改变我们的宇宙的直接图像。 这项探索拨款研究计划的目标是利用新型低频射电干涉仪--再电离阵列(HERA)的氢纪元数据，将21厘米宇宙学的长期愿景转化为观测现实。在这一批款期内将开展的短期活动包括： (1)提供一个软件流水线，用于将HERA原始数据缩减为宇宙黎明的第一个直接图像和统计量，如功率谱测量。 (2)分析和解释产生的功率谱，以确定第一代星系的性质，如它们的典型质量、它们的星系团和它们的发射性质。与其他宇宙学探测器(如宇宙微波背景)对接，对中微子质量等基本参数产生更严格的约束。 (3)结合机器学习技术，开发21厘米宇宙学的新一代分析技术。将图像识别技术应用于宇宙黎明的图像，超越了功率谱分析。使用机器学习来帮助设计和优化下一代望远镜。 这笔赠款将为21厘米宇宙学新兴领域的本科生、研究生和博士后研究员提供培训。他们的专业知识和作为这项建议的一部分开发的分析工具将提供给加拿大在21厘米宇宙学领域的大型存在，包括CHINE、Murchison Widefield阵列和平方千米阵列。

Cosmologists have now observed both the Universe today as well as its primordial conditions. However, the crucial epoch of Cosmic Dawn---the period when the first stars and galaxies illuminated our Universe---remains unobserved. As a result, we remain ignorant of how modern astronomical structures came to be. For instance, what was the nature of the first galaxies? Were they primarily large galaxies or a broader population of smaller ones? What role, if any, did the particle physics of neutrinos and (possibly) annihilating dark matter play in this era? My research program unlocks the era of Cosmic Dawn to direct observations. We do so via 21cm tomography, where faint radio emission from neutral hydrogen atoms are used to make large scale maps of our Universe. These maps then provide a direct picture of how first-generation galaxies illuminated, ionized, and permanently altered our cosmos. This Discovery Grant research program targets the opportunity to turn the long-term vision of 21cm cosmology into observational reality using data from the Hydrogen Epoch of Reionization Array (HERA), a novel low-frequency radio interferometer. The short-term activities to be undertaken in this grant period are to: (1) Deliver a software pipeline for reducing raw HERA data into the first direct images of Cosmic Dawn and statistical quantities such as a power spectrum measurement. (2) Analyze and interpret the resulting power spectra to determine the properties of first-generation galaxies, such as their typical mass, their clustering, and their emission properties. Interface with other cosmological probes (such as the Cosmic Microwave Background) to produce sharpened constraints on fundamental parameters such as the neutrino mass. (3) Incorporate machine learning techniques to develop next-generation analysis techniques for 21cm cosmology. Move beyond power spectrum analyses by applying image-recognition techniques to images of Cosmic Dawn. Use machine-learning to aid in the design and optimization of next-generation telescopes. This grant will provide training for undergraduates, graduate students, and postdoctoral fellows in the emerging field of 21cm cosmology. Their expertise and the analysis tools that are developed as part of this proposal will be made available to the large Canadian presence in 21cm cosmology, including CHIME, the Murchison Widefield Array, and the Square Kilometre Array.