Dark matter in spiral galaxies. I - Galaxies with optical rotation curves

Data obtained with a CCD camera are presented for 37 Sb and Sc galaxies with existing optical rotation curves. The CCD images are used to derive luminosity profiles using standard reduction methods, and multicolor images are obtained for several galaxies in order to investigate the effects of color gradients. A new method for decomposing the profiles into bulge and disk components is presented. It is found that optical rotation curves do not always place strong constraints on the amount of dark matter in galaxies. Three methods of constraining the halo or bulge/disk parameters are presented. The stellar M/L ratio is shown to correlate with galaxy mass, morphological type, and inclination.