  We recover spiral and barred spiral patterns in disk galaxy simulations with
a Wave Dark Matter (WDM) background (also known as Scalar Field Dark Matter
(SFDM), Ultra-Light Axion (ULA) dark matter, and Bose-Einstein Condensate (BEC)
dark matter). Here we show how the interaction between a baryonic disk and its
Dark Matter Halo triggers the formation of spiral structures when the halo is
allowed to have a triaxial shape and angular momentum. This is a more realistic
picture within the WDM model since a non-spherical rotating halo seems to be
more natural. By performing hydrodynamic simulations, along with earlier test
particles simulations, we demonstrate another important way in which wave dark
matter is consistent with observations. The common existence of bars in these
simulations is particularly noteworthy. This may have consequences when trying
to obtain information about the dark matter distribution in a galaxy, the mere
presence of spiral arms or a bar usually indicates that baryonic matter
dominates the central region and therefore observations, like rotation curves,
may not tell us what the DM distribution is at the halo center. But here we
show that spiral arms and bars can develop in DM dominated galaxies with a
central density core without supposing its origin on mechanisms intrinsic to
the baryonic matter.
