Introducing the Cloud Factory: How galactic scale forces affect cloud morphology and dynamics

I present a new suite of simulations that resolve individual molecular clouds down to ~0.1 pc scales while they are embedded within a Spiral Galaxy. This uniquely enables us to study fragmentation and star formation within the resolved clouds in their true galactic context for the first time and is a perfect point of comparison to ISM observations in the ALMA era. Our Arepo simulations include a time-dependent chemical model, gas self-gravity, the ISRF and gas self-shielding, magnetic fields, sink particles, supernova feedback, and photo-ionisation from sinks. Using an analytic Milky-Way like spiral potential as our base, we turn on these effects step-by-step in a series of simulations to create a laboratory for testing the physics of the ISM and star formation from kpc scales to cold cores. The molecular clouds formed in our galaxy scale simulations consist of networks of velocity coherent filaments, as seen in observations. In regions with high turbulence from supernova feedback the filaments within the clouds are shorter and less aligned than those in more quiescent regions dominated by the galactic potential. Stars form in all cases, but are more likely to form at the junctions of filaments in the feedback dominated case. To investigate how the turbulence driven by the large scale forces compares to observations we perform non-LTE line transfer to calculate the CO emission, and then compare to observed data using PCA and the Turbustat package. A good match to observed size-linewidth relations is found only when there is both self-gravity and previous turbulent mixing from supernova. I will then investigate how different magnetic field strengths impacts on the formation of molecular clouds, the star formation rate given by sink particles, and the orientation of filamentary structures. Finally I will show early results extending our Cloud Factory simulations to low metallicity dwarf galaxies.