Evolution of Galaxies Across Mass and Time

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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.**