Evolution of Galaxies Across Mass and Time

了解星系是如何形成和演化的，对于现代天体物理学和我们对自己的起源和在宇宙中的位置的理解都是至关重要的。为了理解所涉及的过程，我们必须探索参数空间的两个关键领域：(a)作为星系质量函数的演化，从低质量星系到超大质量、罕见的怪物，以及(b)从宇宙再电离时代（z bbb70）的物体一直到现在的宇宙时间演化。时间和质量当然是耦合的，因为星系通过恒星形成和合并增加了它们的质量，所以我们必须同时研究它们。在接下来的几年里，我的学生、同事和我将使用(1)对非常大的星系样本进行统计分析的能力，然后，(2)詹姆斯·韦伯太空望远镜（JWST）卓越的灵敏度和分辨率，对关键的子样本进行详细的后续工作。这项工作将围绕两个最先进的、独特的数据集进行构建——一个具有前所未有的统计能力，另一个对关键子样本进行了大量的详细研究：***(1)使用斯巴鲁HSC调查（HSC）探索星系转换。HSC是一个非常大，非常深入的多年调查，最近由斯巴鲁望远镜上的新HSC宽视场成像仪开始。虽然HSCS数据将由日本+普林斯顿HSCS团队专有，但我领导的加拿大+法国+中国团队已获得数据访问权限，以换取为该项目提供深CFHT u波段成像。我们的项目名为clads （CFHT大面积u波段深度调查），目前正在收集数据，将在2年内进行60个黑夜的观测。我们的科学重点将是利用统计学的力量（例如，我们将有几百万个光度红移到z>1）来了解高红移星系在不同种群（质量，恒星形成率，形态，环境）之间如何随时间流动。***(2)利用JWST保证时间观测（GTO）和NIRISS无缝隙光谱仪对细节进行归零。GTO的数据将是JWST获得的首批数据之一，它将让我们在高红移的情况下更加详细地了解星系的转变过程。我们的NIRISS观测将与其他GTO团队协调，采用多技术方法进行全面分析。虽然JWST的视野很小，但它将具有前所未有的灵敏度和空间分辨率，这将使我们能够通过旨在识别正在进行的星系生长和转化过程的特征（形态学，光谱，光谱形态学）的研究，跟踪我们从统计大范围工作（例如，hsc + clads，上图）中获得的见解。***总之，未来几年将是星系形成和演化研究领域的一个极好的时期。我和我的学生、同事们都有得天独厚的优势，可以利用这两种极其强大的资源，站在这项工作的最前沿

Understanding how galaxies form and evolve is central to both modern astrophysics and to our understanding of our own origins and place in the Universe. To understand the processes involved we must explore two key domains of parameter space: (a) evolution as a function of galaxy mass, from low-mass galaxies to the ultra-massive, rare monsters, and (b) evolution over cosmic time from objects in the epoch of cosmic reionization (z>7) all the way to the present day. Time and mass are of course coupled as galaxies grow their masses through star formation and mergers and so we must study them in tandem.***Over the next several years my students, colleagues, and I will use (1) the power of statistical analysis on very large galaxy samples and, then, (2) the superb sensitivity and resolution of the James Webb Space Telescope (JWST) for detailed follow-up work on key subsamples. The work will be structured around two state-of-the-art, unique datasets - one of unprecedented statistical power, the other reaching immense detail on key subsamples: ***(1) Exploring galaxy transformations using the Subaru HSC Survey (HSCS). The HSCS is a very large, very deep multi-year survey recently started with the new HSC wide-field imager on the Subaru telescope. While the HSCS data will be proprietary to its Japan+Princeton HSCS team, I lead a Canada+France+China team that has secured data access in exchange for contributing deep CFHT U-band imaging to the project. Our project, dubbed CLAUDS (CFHT Large Area U-band Deep Survey) is now taking data and will take 60 dark-time nights over 2 years. Our science focus will be to use the power of statistics (e.g., we will have several million photometric redshifts to z>1) to understand how high-redshift galaxies flow between various populations (mass, star formation rate, morphology, environment) over time. ***(2) Zeroing in on the details using JWST Guaranteed Time Observations (GTO) with the NIRISS slitless spectrograph. The GTO data will be among the first JWST data taken and will let us zero-in on the galaxy-transformation processes at high redshift in much more detail then is currently possible. Our NIRISS observations will coordinate with other GTO teams for a comprehensive analyses with a multi-technique approach. While JWST will have a small field of view, it will have unprecedented sensitivity and spatial resolution that will let us follow-up the insights we gain from statistical large-area work (e.g., HSCS+CLAUDS, above) through studies that aim to identify the signatures (morphological, spectral, spectro-morphological) of the galaxy growth and transformation processes underway. ***In sum, the coming years will be a fantastic time in the field of galaxy formation and evolution research. Building on privileged access to two immensely powerful resources my students, colleagues and I are well positioned to be at the forefront of this work.**