  Low Surface Brightness (LSB) galaxies are dominated by dark matter.
High-resolution rotation curves suggest that their total mass-density
distributions are dominated by constant density cores rather than the steep and
cuspy distributions found in Cold Dark Matter (CDM) simulations. The data are
best described by a model with a soft core with an inner power-law mass-density
slope alpha = 0.2 +/- 0.2. However no single universal halo profile provides an
adequate description of the data. The observed mass profiles appear to be
inconsistent with LambdaCDM.
