  Nonthermal fixed points of far-from-equilibrium dynamics of a dilute
degenerate Bose gas are analysed in two and three spatial dimensions. For such
systems, universal power-law distributions, previously found within a
nonperturbative quantum-field theoretic approach, are shown to be related to
vortical dynamics and superfluid turbulence. The results imply an
interpretation of the momentum scaling at the nonthermal fixed points in terms
of independent vortex excitations of the superfluid. Long-wavelength acoustic
excitations on the top of these are found to follow a non-thermal power law.
The results shed light on fundamental aspects of superfluid turbulence and have
strong potential implications for related phenomena studied, e.g., in
early-universe inflation or quark-gluon plasma dynamics.
