Modelling rotation curves -- the turbulent way

Abstract

Helical hydrodynamic turbulence can magnify perturbation seed eddies and this can lead to the appearance of large scale structures. The evolution of the instability is accompanied by a transfer of energy from small scale to large scale fluid motions. This has motivated us to explore the possibility of explaining the formation of large scale structures in the universe as a result of such an 'inverse cascade'. As a first step in this direction we have modeled the rotation curves of two galaxies by combining the effects of rigid rotation, gravity and turbulence. The model has yielded very good estimates for the parameters like the galaxy-mass, turbulent velocity and the angular velocity of the galaxies. This encourages us to study the velocity fields on larger scales such as those of clusters and superclusters to vindicate the model's predicted spectrum