Wobbling galaxy spin axes in dense environments
  The orientation of galaxy spin vectors within the large scale structure has
been considered an important test of our understanding of structure formation.
We investigate the angular changes of galaxy spin vectors in clusters - denser
environments than are normally focused upon, using hydrodynamic zoomed
simulations of 17 clusters YZiCS and a set of complementary controlled
simulations. The magnitude by which galaxies change their spin vector is found
to be a function of their rotational support with larger cumulative angular
changes of spin vectors when they have initially lower $V_{\theta}/\sigma$. We
find that both mergers and tidal perturbations can significantly swing spin
vectors, with larger changes in spin vector for smaller pericentre distances.
Strong tidal perturbations are also correlated with the changes in stellar mass
and specific angular momentum of satellite galaxies. However, changes in spin
vector can often result in a canceling out of previous changes. As a result,
the integrated angular change is always much larger than the angular change
measured at any instant. Also, overall the majority of satellite galaxies do
not undergo mergers or sufficiently strong tidal perturbation after infall into
clusters, and thus they end up suffering little change to their spin vectors.
Taken as a whole, these results suggest that any signatures of spin alignment
from the large scale structure will be preserved in the cluster environment for
many gigayears.
