EPoS Contribution
EPoS Contribution
Revealing the formation and properties of GMCs through galaxy simulations

Clare Dobbs
University of Exeter, Exeter, UK
Global disk simulations allow a unique opportunity to investigate the formation and properties of GMCs, given the difficulties of observing GMCs and the limited sample of galaxies available for observations. I will present calculations showing that both the agglomeration of smaller clouds into larger structures, and self gravity, contribute to GMC formation. Agglomeration occurs providing there is a cold, clumpy component of the ISM, and is much more effective in spiral shocks, where collisions between clumps are more frequent. Self gravity becomes increasingly important as the disk surface density increases. Properties of GMCs formed in these simulations also vary according to how they are formed, depending on the thermal nature of the ISM, surface density and spiral shock strength. The shock strength is the predominant factor when agglomeration is the key process for forming GMCs, determining the size and spacing of GMCs along the spiral arms. Further properties relevant to star formation, such as the angular momentum and morphology of the clouds, also depend on the surface density and thermal distribution of the ISM. Interestingly when the gas is clumpy, collisions can lead to retrograde rotating GMCs. Finally, the amount of gravitationally bound gas in these simulations provides an indication of the degree of star formation expected to occur in the GMCs under different galactic conditions.