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Date and Time of the Query: 2019-05-20 T08:11:27 PDT
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For refcode 2013A&A...557A.131M:
Retrieve 30 NED objects in this reference.
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2013A&A...557A.131M The DiskMass Survey. VII. The distribution of luminous and dark matter in spiral galaxies Martinsson, Thomas P. K.; Verheijen, Marc A. W.; Westfall, Kyle B.; Bershady, Matthew A.; Andersen, David R.; Swaters, Rob A. Abstract. We present dynamically-determined rotation-curve mass decompositions of 30 spiral galaxies, which were carried out to test the maximum-disk hypothesis and to quantify properties of their dark-matter halos. We used measured vertical velocity dispersions of the disk stars to calculate dynamical mass surface densities (Sigma_dyn_). By subtracting our observed atomic and inferred molecular gas mass surface densities from Sigma_dyn_, we derived the stellar mass surface densities (Sigma_*_), and thus have absolute measurements of all dominant baryonic components of the galaxies. Using K-band surface brightness profiles (I_K_), we calculated the K-band mass-to-light ratio of the stellar disks (Upsilon_*_ = Sigma_*_/I_K_) and adopted the radial mean (overline{mls}) for each galaxy to extrapolate Sigma_*_ beyond the outermost kinematic measurement. The derived overline{mls} of individual galaxies are consistent with all galaxies in the sample having equal Upsilon_*_. We find a sample average and scatter of mlab overline{mls}mrab = 0.31 +/- 0.07. Rotation curves of the baryonic components were calculated from their deprojected mass surface densities. These were used with circular-speed measurements to derive the structural parameters of the dark-matter halos, modeled as either a pseudo-isothermal sphere (pISO) or a Navarro-Frenk-White (NFW) halo. In addition to our dynamically determined mass decompositions, we also performed alternative rotation-curve decompositions by adopting the traditional maximum-disk hypothesis. However, the galaxies in our sample are submaximal, such that at 2.2 disk scale lengths (h_R_) the ratios between the baryonic and total rotation curves (F_b_^2.2h_R_^) are less than 0.75. We find this ratio to be nearly constant between 1-6h_R_ within individual galaxies. We find a sample average and scatter of mlab F_b_^2.2h_R_^mrab = 0.57 +/- 0.07, with trends of larger F_b_^2.2h_R_^ for more luminous and higher-surface-brightness galaxies. To enforce these being maximal, we need to scale Upsilon_*_ by a factor 3.6 on average. In general, the dark-matter rotation curves are marginally better fit by a pISO than by an NFW halo. For the nominal-Upsilon_*_ (submaximal) case, we find that the derived NFW-halo parameters have values consistent with LambdaCDM N-body simulations, suggesting that the baryonic matter in our sample of galaxies has only had a minor effect on the dark-matter distribution. In contrast, maximum-Upsilon_*_ decompositions yield halo-concentration parameters that are too low compared to the LambdaCDM simulations. Appendix is available in electronic form at http://www.aanda.org Key words: techniques: imaging spectroscopy, galaxies: spiral, galaxies: structure, galaxies: kinematics and dynamics, galaxies: fundamental parameters
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Please click here for ADS abstract

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