Exploring Cosmic Noon and Cosmic Dawn with JWST Guaranteed Time Observations

当詹姆斯·韦伯太空望远镜(JWST)于2021年发射时，它将改变我们对遥远宇宙的理解。自2003年以来，作为JWST NIRISS团队(NIRISS=近红外成像仪和无缝隙光谱仪)的核心和创始团队成员，我一直期待着加拿大对JWST的贡献。我们将使用我们团队保证时间观测者(GTO)分配的200小时来执行一个专门的计划，研究跨宇宙时间的低质量星系的演化。在加拿大近一半的GTO时间里，这些数据对我的团队来说是一个千载难逢的机会。在这笔赠款的期限内，我们还将完成一些正在进行的关键项目，这些项目使用大规模的Clauds+HSC成像数据集，以前所未有的深度和面积组合探测遥远的宇宙，然后将向社区公开发布这一奇妙的数据集。我们还将继续为双子座开发GIRMOS仪器，2024年年中将迎来曙光，随后将在下一个(2025+)任期内对其进行科学利用。然而，2020-2025年这一期间的主要重点将是对JWST GTO数据集的科学利用。这项工作将集中于低质量星系的演化和作用，低质量星系是宇宙中数量最多的星系。这个项目的主要目标是了解它们的性质、影响和随宇宙时间的演变。我们将使用我们的JWST GTO数据来研究遥远的低质量星系，其中许多星系是引力透镜的，有些是壮观的透镜，位于五个大质量星系团的后面。这将产生10,000个星系的光谱和100,000个遥远星系的图像，从再电离时代(“宇宙黎明”)到z~2-3的“宇宙中午”，到大质量z~0.5透镜星系团内的星系群。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的内在敏感性，也是因为引力透镜带来的额外推动--对于我们的许多星系来说。这些数据将产生许多星系的发射线地图和线比率，其中一些是在~100pc的空间尺度上的，这将让我们确定Z~2-5星系中恒星形成、尘埃和金属的空间分布，并追踪它们如何在宇宙时间内演化。我们还将探测和描述再电离时代的星系，使用多次成像的透镜星系来约束星系团的质量分布和暗物质亚结构，并研究最大质量星系团中恒星形成的猝灭。“宝藏”一词经常被用来描述来自大型调查的数据，但我们的200小时JWST GTO计划超出了这一范围。对于我、我的学生、博士后和合作者来说，这是一个千载难逢的机会。它还将为世界天文学界提供丰富的资源，因为我们将公开发布我们将开发的经过处理的数据产品和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.