Star Formation and ISM in Nearby Galaxies: The PAWS view
Hughes, Leroy, Pety, Colombo, Meidt, Dumas, Dobbs, Schuster,
Thompson, Garcia-Burillo, Kramer, Rix
Most stars are formed in galaxies with stellar masses of 4×1010 solar masses − out to the early universe. Thus the Milky Way can be regarded as a typical representative with a great opportunity to study the formation of the ISM and stars in excellent detail. Unfortunately, due to our location in its disk, the importance of large-scale galactic structure for these formation processes cannot be easily assessed. Here, nearby galaxies provide ideal laboratories to study the influence of large-scale physics for the formation processes. With this in mind we embark on a study of the molecular cloud and star formation processes in the central 9 kpc disk of the nearby galaxy M51a using the IRAM Plateau de Bure interferometer. Our survey (PAWS – PdBI Arcsecond Whirlpool Survey) mapped the molecular gas in its CO(1−0) line emission at ~40 pc resolution down to a mass limit of about 200,000 solar masses - comparable to the size of an average Giant Molecular Cloud (GMC) in the Milky Way. Using this unique dataset in conjunction with existing data at similar angular resolution across the electro-magnetic spectrum new insights into the relation between galactic structures and the formation of GMCs and stars can be gained. I will present our recent results on the GMC population (in comparison to other nearby galaxies), its relation to star formation and the importance of the galactic structure.