  A key feature of ultra-light dark matter composed by bosons is the formation
of superfluid Bose-Einstein condensate (BEC) structures on galactic scales. We
study collisions of BEC solitonic and vortex structures in the framework of the
Gross-Pitaevskii-Poisson model. It is found that the superfluid nature of
bosonic dark matter leads to the formation of quantized vortex lines and vortex
rings in interference patterns formed during collisions. Calculating the
gravitational wave luminosity, we demonstrated that quantum interference
patterns affect notably the gravitational wave radiation.
  We reveal that superfluid self-gravitating BECs can form stable localized
vortex structures which remain robust even after a head-on collision.
