Angular momentum and morphological sequence of massive galaxies through
  Dark Sage
  We study the present-day connection between galaxy morphology and angular
momentum using the {\sc Dark Sage} semi-analytic model of galaxy formation. For
galaxies between $ 10^{11}-10^{12} \mathrm{M}_{\odot}$ in stellar mass, the
model successfully predicts the observed trend whereby galaxies with more
prominent disks exhibit higher {\em stellar} disk specific angular momentum
($j_{\rm stellar, disk}$) at fixed stellar mass. However, when we include the
gas in the disk, bulge-dominated galaxies have the highest {\em total} disk
specific angular momentum ($j_{\rm total, disk}$). We attribute this to a large
contribution from an extended disk of cold gas in typical bulge-dominated
galaxies. We find the relationship between $j_{\rm dark matter}$ and morphology
to be quite complex. Surprisingly, in this stellar mass range, not only do
bulge-dominated galaxies tend to live in halos with higher $j_{\rm dark
matter}$ than disk-dominated galaxies, but intermediate galaxies (those with
roughly equal fractions of bulge and disk mass) have the lowest $j_{\rm dark
matter}$ of all. Yet, when controlling for halo mass, rather than stellar mass,
the relationship between $j_{\rm dark matter}$ and morphology vanishes. Based
on these results, halo mass rather than angular momentum is the main driver of
the predicted morphology sequence at high masses. In fact, in our stellar mass
range, disk-dominated galaxies live in dark matter halos that are roughly
1/10th the mass of their bulge-dominated counterparts.
