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，也观察了它的原始状态。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？它们主要是大型星系还是由更小的星系组成？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，如果有的话？******我的研究项目开启了宇宙黎明时代的直接观测。我们通过21厘米断层扫描来实现这一点，在那里，中性氢原子发出的微弱无线电辐射被用来绘制大尺度的宇宙地图。然后，这些地图提供了第一代星系如何照亮、电离并永久改变我们宇宙的直接图景。******这项发现资助研究计划的目标是利用一种新型低频无线电干涉仪——氢再电离阵列（HERA）的数据，将21厘米宇宙学的长期愿景转化为观测现实。在此拨款期间将进行的短期活动是：******(1)提供一个软件管道，将原始HERA数据简化为宇宙黎明号的第一批直接图像和统计数量，如功率谱测量。******(2)分析和解释所得的功率谱，以确定第一代星系的特性，如它们的典型质量、它们的群集和它们的发射特性。与其他宇宙探测器（如宇宙微波背景）接口，对基本参数（如中微子质量）产生尖锐的约束。******(3)结合机器学习技术开发下一代21cm宇宙学分析技术。通过将图像识别技术应用于宇宙黎明号的图像，超越功率谱分析。利用机器学习来帮助下一代望远镜的设计和优化。******该基金将为21厘米宇宙学这一新兴领域的本科生、研究生和博士后提供培训。他们的专业知识和作为该提案一部分开发的分析工具将提供给加拿大在21厘米宇宙学中的大型存在，包括CHIME，默奇森宽场阵列和平方公里阵列。

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.