Heavy Bars and Light Spirals -- Taking Advantage of Asymmetries in   Galaxies
  I summarize a series of studies where the underlying theme is to exploit non-axisymmetry disk structures such as bars and spiral arms. By measuring the strength of gravitational forces from these structures we can measure the mass in them. The advantage of this approach is that mass to light ratios can be constrained in a way independent of the dark matter profile. By examining a variety of types of galaxies it appears that a correlation between morphology and dark matter fraction emerges. 
A. C. Quillen