A new View of Young galaxies with ALMA and JWST

Introduction

The majority of the Universe’s star formation occurred shrouded in cosmic dust, making it extremely challenging—historically—to obtain a clear view of young (z≳2) galaxy assembly. While the Atacama Large Millimeter Array (ALMA) has already enabled significant progress – including pioneering work by the PI to directly image this dusty star formation in early galaxies – their existing stellar populations remain obscured. At the same time, our understanding of the molecular gas fueling that star formation is still limited to unresolved detections and/or biased tracers.

Breakthrough Opportunities

Fortunately, we are on the verge of a breakthrough with the newly launched James Webb Space Telescope (JWST) and the imminent arrival of ALMA Bands 1&2. To this end, the PI has obtained a suite of competitive proprietary data on JWST, ALMA, and Band 1/2 pilot facilities.

Research Goals

Fully capitalizing on this opportunity now requires a team of capable researchers. By leveraging this data and a novel resolved spectral energy distribution (SED) fitting technique, the proposed program will:

1. Reveal the hidden stellar populations in the dustiest young (z~2.5) galaxies for the first time, testing predictions from hierarchical galaxy formation.
2. Detect and map the crucial CO(1-0) and CO(2-1) emission lines in a statistical sample of these same young galaxies, directly measuring their full cold gas reservoirs via state-of-the-art Bayesian modeling, and calibrating other less-well-understood gas tracers.
3. Push studies of dust and gas in galaxies to the earliest cosmic epochs (z>6.5), including detecting their molecular gas via CO(3-2)—one of the key science goals for ALMA Band 1—thus revealing how the most massive early galaxies grew so quickly.

Conclusion

Given her demonstrated track record leading a group and the wealth of data secured, the PI is optimally placed to take advantage of this unique confluence of revolutionary instruments to provide a completely new view into how young galaxies built up their stellar masses.