Declining simulated rotation curves for spiral galaxies?

Might simulations of galaxie rotation curves indicate no necessity of dark matter; consistent with not gravitationally bound object? Hence consistent with dark matter, critical density, and gravitation not of importance in re-contraction of ‘universe’ scenario?

Perhaps small mirror (20 cm) confirmation of any spectral lines shifting? There might be no significant motion of such gas, assumed representive of entire arm’s motion, rather than just local motion. Especially so, if just angular inertia and circular orbit. Thus if no detected motion of lines, then not consistent with rotation velocities, nor association with any dark matter. Hence possible to construct models without dark matter (not even static DM) with no critical density, nor role for gravitation in a re-contraction scenario?

Declining rotation curves at z=2: A natural phenomenon in ΛCDM cosmology.  Adelheid F. Teklu, Rhea-Silvia Remus, Klaus Dolag, Alexander Arth, Andreas Burkert, Aura Obreja, Felix Schulze. https://arxiv.org/abs/1711.07985