CDM in LSB Galaxies: Toward the Optimal Halo Profile

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.