Exploring Cosmic Noon and Cosmic Dawn with JWST Guaranteed Time Observations

詹姆斯·韦伯太空望远镜（JWST）将于2021年发射，届时它将改变我们对遥远宇宙的理解。自2003年以来，我一直期待着这一天的到来，作为JWST NIRISS团队（NIRISS = Near-IR Imager and Slitless Spectrograph）的核心和创始团队成员，加拿大对JWST的贡献。我们将利用我们团队的保证时间观测者（GTO）分配的200小时来开展一个专门的项目，研究低质量星系在宇宙时间中的演化。在加拿大将近一半的GTO时间里，这些数据对我的团队来说将是一个千载难逢的机会。在这项拨款的期限内，我们还将完成一些正在进行的关键项目，这些项目使用巨大的clads +HSC成像数据集，以前所未有的深度和面积探测遥远的宇宙，然后将这个奇妙的数据集公开发布给社区。我们还将继续为双子座开发GIRMOS仪器，直到2024年中期首次点亮，然后在下一个（2025+）任期内进行科学开发。然而，2020-2025年期间的主要重点将是对JWST GTO数据集的科学利用。这项工作将集中在宇宙中数量最多的低质量星系的演化和作用上。这个项目的主要目标是了解它们的特性、影响和随着宇宙时间的演变。我们将使用我们的JWST GTO数据来研究遥远的低质量星系，其中许多是引力透镜，有些是在五个大质量星系团后面。这将产生1万张光谱和10万个遥远星系的图像，从再电离时代（“宇宙黎明”）到z~2-3的“宇宙正午”，再到z~0.5透镜星团内的星系群。光谱和图像将具有前所未有的空间分辨率和灵敏度，这既是由于JWST固有的灵敏度，也是由于引力透镜带来的额外推动。这些数据将产生许多星系的发射线图和线比，其中一些空间尺度为~100pc，这将使我们确定z~2-5星系中恒星形成、尘埃和金属的空间分布，并追踪它们在宇宙时间中的演变。我们还将探测和表征再电离时代的星系，使用多重成像透镜星系来约束星系团的质量分布和暗物质亚结构，并研究大多数大质量星系团中恒星形成的淬火。“宝库”这个词通常用来描述来自大型调查的数据，但我们200小时的JWST GTO项目不止于此。对我、我的学生、博士后和合作者来说，这是一个千载难逢的机会。它还将为全球天文学界提供丰富的资源，因为我们将公开发布处理后的数据产品和我们将开发的NIRISS数据分析工具。

When it launches in 2021, the James Webb Space Telescope (JWST) is going to transform our understanding of the distant Universe. Since 2003 I have been anticipating this day as core & founding team member of the JWST NIRISS team (NIRISS = Near-IR Imager and Slitless Spectrograph), Canada's contribution to JWST. We will use 200 hours of our team's Guaranteed Time Observer (GTO) allocation to carry out a dedicated program to study the evolution of low-mass galaxies across cosmic time. At nearly half of Canada's GTO time, these data will represent a once-in-a-career opportunity for my group. During the term of this grant we will also finish a number of ongoing key projects that use the massive CLAUDS+HSC imaging dataset that probes the distant universe to an unprecedented combination of depth and area, and will then publicly release this fantastic dataset to the community. We will also continue development of the GIRMOS instrument for Gemini, building up to first light in mid-2024, to be followed by its scientific exploitation during the next (2025+) term. However, the main focus over this term, 2020-2025, will be the scientific exploitation of the JWST GTO dataset. This work will focus on the evolution and role of low-mass galaxies, which are the most numerous galaxies in the Universe. The primary goal of this program is to understand their properties, impact, and evolution over cosmic time. We will use our JWST GTO data to study distant low-mass galaxies, many of them gravitationally lensed, and some spectacularly so, behind five massive galaxy clusters. This will yield spectra of 10,000 and images of 100,000 distant galaxies, from the Epoch of Reionization ("cosmic dawn"), through "cosmic noon" at z~2-3, to the galaxy populations within the massive z~0.5 lensing clusters. The spectra and images will have unprecedented spatial resolution and sensitivity, both due to JWST's intrinsic sensitivity and - for many of our galaxies - because of the additional boost due to the gravitational lensing. The data will yield emission line maps and line ratios for many galaxies, some at spatial scales of ~100pc, that will let us determine the spatial distribution of star formation, dust, and metals in z~2-5 galaxies and trace how they evolve across cosmic time. We will also detect and characterize galaxies in the Epoch of Reionization, use multiply-imaged lensed galaxies to constrain cluster mass distributions and dark matter substructure, and study the quenching of star formation in the most massive galaxy clusters. The words "treasure-trove" are often used to describe data from large surveys, but our 200-hr JWST GTO program goes beyond this. It is a once-in-a-career opportunity for me, my students, postdocs, and collaborators. It will also provide a rich resource for the world-wide astronomy community as we will publicly release the processed data products and NIRISS data analysis tools that we will develop.