Mapping Molecular ISM in the Whole Disk of the Barred Spiral Galaxy M83

Giant molecular clouds (GMCs) are an important factor in star formation in spiral galaxies and in the evolution of those galaxies. This project will use high resolution observations from the ALMA radio telescope to map out the CO gas content in M83 -- a nearby spiral galaxy. These observations will identify every GMC in this galaxy down to the lowest masses of 10,000 solar masses. This map will provide new insights on the connection between GMCs, star formation, spiral arms, and galaxy evolution. The project will also develop and provide support for radio instruments for educational uses in university courses. The project will take an unbiased census of the bulk molecular gas over the whole disk of M83, resolving the GMC distribution, scaling relations, mass function, and their spatial variations. It will characterize the CO 2-1/1-0 line ratio of every GMC over the whole disk and investigate its variations as a function of galactic structures and star formation activity. The simultaneous analysis of CO(1-0) and CO(2-1) over the entire disk will provide unique reference for future studies of ISM evolution in galaxies. The project will upgrade and redesign an educational radio interferometer for use in university courses. Part of this upgrade will be to shift the operating frequency to a band that is protected for research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.