Observing the Birth of Massive Galaxies at Cosmic Dawn and Maximizing Canada's Investment in JWST and Euclid

星系是恒星和行星的宿主，是我们宇宙结构的基石。我们是银河系的居民，银河系是一个相对大小的星系，这意味着 建立对大质量星系如何形成和演化的坚定理解，对于理解人类在宇宙中的位置至关重要。在过去十年中，星系形成研究取得了巨大进展，这在很大程度上得益于近红外成像和光谱能力的进步。这些进展使我们能够观察最遥远的星系，由于光的传播时间有限，这些星系就像“时光机”，直接向我们展示了它们形成的最早阶段。虽然我们还在继续学习，但仍有许多基本问题我们没有答案：第一个大质量星系是什么时候形成的？这个过程是什么样子的？为什么大质量星系停止形成恒星？大质量星系和生活在其中的超大质量黑洞是如何共同进化的？ 仅使用地面数据来回答这些问题正变得越来越具有挑战性。然而，红外线研究的前景在未来几年将发生戏剧性的变化。2018年10月，NASA将发射詹姆斯·韦伯太空望远镜(JWST)，这是哈勃太空望远镜(HST)的6.5米中红外优化继任者。加拿大是JWST协作的成员，出资1.5亿美元提供了关键仪器。几年后，在2020年底，欧洲航天局发射了欧几里德望远镜，这是一种类似于HST的广视场望远镜，将在大约三分之一的夜空中获得哈勃质量的观测。加拿大也是欧几里德联盟的成员，承诺提供约150万美元的地面成像数据来支持这项任务。 这些望远镜将彻底改变我们对遥远宇宙的理解；然而，如果在发射前不对研究进行重大投资，我们将无法充分利用这些天文台有限的寿命。特别是，JWST需要使用我们最好的地面观测来预先选择光谱目标，而欧几里德需要优化数据分析算法。 我未来5年的研究目标有两个。首先，使用正在进行的、最近批准的度级地面红外成像观测，如UltraVISTA-E和VILES，对大质量星系的生长及其高红移特性进行最全面的研究(z&gt；4)。此后，从这些数据集中发现的高红移、大质量星系将成为JWST光谱观测的理想目标。其次，我计划利用最近对遥远星系团的HST观测来约束环境如何阻止星系形成恒星的天体物理学，并使用这些数据来验证和优化欧几里德的星系团探测算法。

Galaxies are host to the stars and planets, and are the building blocks of structure in our Universe. We are residents of the Milky Way, a relatively massive galaxy which means developing a firm understanding of how massive galaxies form and evolve is essential for understanding humankind's place in the cosmos. In the last decade enormous progress has been made in the study of galaxy formation aided in large part by advancements in near-infrared imaging and spectroscopic capabilities. These advances have allowed us to look at the most distant galaxies, which due to the finite travel time of light, act as "time machines" which show us the earliest stages of their formation directly. While we continue to learn much, there are still many basic questions we do not have the answer to: When do the very first massive galaxies form? What does that process look like? Why do massive galaxies stop forming stars? And how do massive galaxies and the supermassive black holes that live within them co-evolve? Answering these questions using ground-based data alone is becoming increasingly challenging. However, the landscape for infrared studies will change dramatically in the coming years. In October 2018, NASA will launch the James Webb Space Telescope (JWST), the 6.5m mid-infrared optimized successor to the Hubble Space Telescope (HST). Canada is a member of the JWST collaboration, having contributed key instrumentation at a cost of $150 million. A few years later in late 2020, the European Space Agency with launch Euclid, a wide-field telescope similar to the HST which will obtain Hubble-quality observations over about one-third of the night sky. Canada is also a member of the Euclid consortium via a commitment to provide ~$1.5m dollars of ground-based imaging data to support the mission. These telescopes will revolutionize our understanding of the distant universe; however, without significant investments in research before their launch, we will not be able to take full advantage of the limited lifetime of these observatories. In particular, JWST requires the pre-selection of spectroscopic targets using our best ground-based observations, and Euclid requires the optimization of data analysis algorithms. The goal of my research over the next 5 years is two-fold. Firstly, to use observations from ongoing, and recently-approved degree-scale, ground-based infrared imaging surveys such as UltraVISTA-E and VEILS to make the most comprehensive study of the growth of massive galaxies and their properties at high redshift (z > 4). Thereafter, the high-redshift, massive galaxies discovered from these datasets will be ideal targets for spectroscopic observations with JWST. Secondly, I plan to exploit recent HST observations of distant galaxy clusters to constrain the astrophysics of how environment stops galaxies from forming stars, and also use those data to validate and optimize cluster detection algorithms for Euclid.