Description:

A decade ago, large surveys of cold gas in other galaxies achieved physical resolution of order a kiloparsec. Large mapping surveys mostly focused on tracers of the bulk molecular and atomic gas, while surveys focused on dense gas mostly integrated over whole galaxies (often LIRGs or ULIRGs). With the mm/sub-mm revolution ushered in by ALMA (as well as new instrumentation on the IRAM facilities and the GBT) this is changing. I will present some first results from PHANGS-ALMA, an ALMA large program that is surveying 80 of the nearest star-forming disk galaxies in CO emission with resolution ~50-100 pc (1"). PHANGS-ALMA gives us a "cloud scale" view of the cold gas across the local galaxy population. We are using this to measure how the cloud-scale properties of cold gas depend on local environment and how they affect star formation. With this sharp view, the evolution of individual star forming regions also comes into focus, allowing access to the time domain and modeling of molecular cloud life cycles. I will describe the survey and show first results, including measurements line width and surface density from ~30,000 individual cloud-sized beams, the implied efficiency per free fall time, the overlap between Halpha (tracing massive star formation) and molecular clouds, the connection to the fraction of dense, star forming gas, and the link between molecular cloud properties and environment.

Speaker: Adam Leroy, The Ohio State University

Host: Cliff Johnson

Keywords: Physics, Astronomy, Astrophysics