Institute for Advanced Study / Princeton University Joint Astrophysics Colloquium

The gas-star formation-feedback "matter cycle" acts in many ways as the engine of galaxy evolution. Over the last decade, the PHANGS surveys have carried out surveys across the electromagnetic spectrum aimed at resolving galaxies into the fundamental units of this cycle: molecular clouds, HII regions, and star clusters. I will describe some of the key results from these surveys, emphasizing our new, dynamic view of molecular clouds from the PHANGS-ALMA CO survey and the new view of dust revealed by PHANGS-JWST. Based on these surveys, we have our first "big picture" view of the demographics of star-forming molecular clouds, which show a clear link to their larger scale environment. The properties of these clouds, and the contrast between tracers of gas and recent star formation reveal the efficiencies and timescales for star formation, highlighting some tension between the data and popular turbulent models of star formation. The key role of stellar feedback is also visible on multiple scales from these data. Feedback helps maintain the large scale dynamical equilibrium in galaxy disks, rapidly reshapes molecular clouds, and carves pervasive shells and bubbles through the ISM. In all of these areas the revolutionary resolution and sensitivity of JWST through the near and mid-infrared promise to enable the next advances. In this area, I will highlight the PHANGS Cycle 1 and 2 JWST Treasuries, which provide high quality, immediately public near- and mid-IR imaging of a representative sample of z=0 star forming galaxies. There will be pretty pictures of galaxies from across the spectrum!