The Impact of Galactic Disc Environment on Star-Forming Clouds
  We explore the effect of different galactic disc environments on the
properties of star-forming clouds through variations in the background
potential in a set of isolated galaxy simulations. Rising, falling and flat
rotation curves expected in halo dominated, disc dominated and Milky Way-like
galaxies were considered, with and without an additional two-arm spiral
potential. The evolution of each disc displayed notable variations that are
attributed to different regimes of stability, determined by shear and
gravitational collapse. The properties of a typical cloud were largely
unaffected by the changes in rotation curve, but the production of small and
large cloud associations was strongly dependent on this environment. This
suggests that while differing rotation curves can influence where clouds are
initially formed, the average bulk properties are effectively independent of
the global environment. The addition of a spiral perturbation made the greatest
difference to cloud properties, successfully sweeping the gas into larger,
seemingly unbound, extended structures and creating large arm-interarm
contrasts.
