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We present dynamically-determined rotation-curve mass decompositions of 30spiral galaxies, which were carried out to test the maximum-disk hypothesis andto quantify properties of their dark-matter (DM) halos. We used measuredvertical velocity dispersions of the disk stars to calculate dynamical masssurface densities. Together with our atomic and molecular gas mass surfacedensities, we derived the stellar mass surface densities, and thus haveabsolute measurements of all dominant baryonic components. Using K-band surfacebrightness profiles, we calculated the K-band mass-to-light ratio of thestellar disks (M/L). Our result is consistent with all galaxies in the samplehaving equal M/L, with a sample average and scatter of <M/L>=0.31+/-0.07.Rotation-curves of the baryonic components were calculated from their masssurface densities, and used with circular-speed measurements to derive thestructural parameters of the DM halos, modeled as either a pseudo-isothermalsphere (pISO) or an NFW halo. All galaxies in our sample are submaximal, suchthat at 2.2 disk scale lengths (hR) the ratios between the baryonic and totalrotation-curves (Fb^{2.2hR}) are less than 0.75. We find this ratio to benearly constant between 1-6 hR within individual galaxies. We find a sampleaverage and scatter of <Fb^{2.2hR}>=0.57+/-0.07, with trends of largerFb^{2.2hR} for more luminous and higher-surface-brightness galaxies. To enforcethese being maximal, we need to scale M/L by a factor 3.6 on average. The DMrotation curves are marginally better fit by a pISO than by an NFW halo. Forthe nominal-M/L (submaximal) case, the derived NFW-halo parameters have valuesconsistent with LCDM N-body simulations, suggesting that the baryonic matterhas only had a minor effect on the DM distribution. In contrast, maximum-M/Ldecompositions yield halo concentrations that are too low compared to the LCDMsimulations.

The DiskMass Survey. VII. The distribution of luminous and dark matter in spiral galaxies