The ALMA view of GMCs in NGC 300: Physical Properties and Scaling
  Relations at 10 pc Resolution
  We have conducted a $^{12}$CO(2-1) survey of several molecular gas complexes
in the vicinity of H II regions within the spiral galaxy NGC 300 using the
Atacama Large Millimeter Array. Our observations attain a resolution of 10 pc
and 1 km s$^{-1}$, sufficient to fully resolve Giant Molecular Clouds (GMCs),
and are the highest to date obtained beyond the Local Group. We use the CPROPS
algorithm to identify and characterize 250 GMCs across the observed regions.
GMCs in NGC 300 appear qualitatively and quantitatively similar to those in the
Milky Way disk: they show an identical scaling relationship between size $R$
and linewidth $\Delta V$ ($\Delta V \propto R^{0.48\pm0.05}$), appear to be
mostly in virial equilibrium, and are consistent with having a constant surface
density of $60$ M$_{\odot}$ pc$^{-2}$. The GMC mass spectrum is similar to
those in the inner disks of spiral galaxies (including the Milky Way). Our
results suggest that global galactic properties such as total stellar mass,
morphology, and average metallicity may not play a major role in setting GMC
properties, at least within the disks of galaxies on the star-forming main
sequence. Instead, GMC properties may be more strongly influenced by local
environmental factors such as the mid-plane disk pressure. In particular, in
the inner disk of NGC 300 we find this pressure to be similar to that in the
local Milky Way but markedly lower than that in the disk of M51 where GMCs are
characterized by systematically higher surface densities and a higher
coefficient for the size-linewidth relation.
