A Revolutionary New Window on the First Galaxies

Despite great progress over the past two decades, we still lack a complete view of galaxies within the first 2 Gyr of cosmic history, at z>3. At those redshifts, we currently only have access to rest-frame ultra-violet light with data from the Hubble Space Telescope (HST), severely limiting our physical understanding of early galaxy build-up. Additionally, it has become clear that HST has been missing a population of particularly red galaxies at z>3 that are either heavily dust-obscured or already turned passive. The long-awaited multibillion-dollar James Webb Space Telescope (JWST) is finally about to launch end of this year. With its enormous gains in sensitivity and in wavelength coverage compared to the current HST+Spitzer data, JWST will completely revolutionize our view and understanding of the first generations of galaxies. At the University of Geneva, I am leading three of the first programs to be executed with JWST after mid 2022, including two of the largest legacy programs. Additionally, I am heavily involved in several more medium and large programs. We will obtain the first wide-area imaging over 0.4 sq.degs as well as an ambitious spectroscopic program that will result in the first complete, emission line selected galaxy samples at z=5-9. In order to analyze these exciting JWST data and deliver high-level science products to the community, I propose to build a small, but efficient project team. Building on my previous research experience, we will exploit the upcoming, revolutionary JWST data to achieve three key goals: (1) constraining when galaxies first started to form stars at cosmic dawn, (2) obtaining the first complete census of galaxies at z~3-7, and (3) a spectroscopic characterization of galaxies during the reionization epoch, at z>6. The coming years represent the start of a golden era for early universe science. With my research group we will strengthen the position of Swiss Astronomy to perform frontier science at the cosmic dawn using the revolutionary upcoming facilities.