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dc.creatorPizagno, James
dc.creatorPrada, Francisco
dc.creatorWeinberg, David H.
dc.creatorRix, Hans-Walter
dc.creatorHarbeck, Daniel
dc.creatorGrebel, Eva K.
dc.creatorBell, Eric F.
dc.creatorBrinkmann, Jon
dc.creatorHoltzman, Jon
dc.creatorWest, Andrew
dc.identifier.citationJames Pizagno et al, "Dark Matter and Stellar Mass in the Luminous Regions of Disk Galaxies," The Astrophysical Journal 633, no. 2 (2005), doi:10.1086/491614en_US
dc.description.abstractWe investigate the correlations among stellar mass (M*), disk scale length (R_d), and rotation velocity at 2.2 disk scale lengths (V_2.2) for a sample of 81 disk-dominated galaxies (disk/total ≥ 0.9) selected from the SDSS. We measure V_2.2 from long-slit Hα rotation curves and infer M* from galaxy i-band luminosities (L_i) and g - r colors. We find logarithmic slopes of 2.60 ± 0.13 and 3.05 ± 0.12 for the (forward fit) L_i-V_2.2 and M*-V_2.2 relations, somewhat shallower than most previous studies, with intrinsic scatter of 0.13 and 0.16 dex, respectively. Our direct estimates of the total-to-stellar mass ratio within 2.2R_d, assuming a Kroupa IMF, yield a median ratio of 2.4 for M* > 10^10 Msun and 4.4 for M* = 10^9-10^10 Msun, with large scatter at a given M* and R_d. The typical ratio of the rotation speed predicted for the stellar disk alone to the observed rotation speed at 2.2R_d is ~0.65. The distribution of scale lengths at fixed M* is broad, but we find no correlation between disk size and the residual from the M*-V_2.2 relation, implying that the M*-V_2.2 relation is an approximately edge-on view of the disk galaxy fundamental plane. Independent of the assumed IMF, this result implies that stellar disks do not, on average, dominate the mass within 2.2R_d. We discuss our results in the context of infall models where disks form in adiabatically contracted cold dark matter halos. A model with a disk-to-halo mass ratio m_d = 0.05 provides a reasonable match to the R_d-M* distribution for spin parameters λ ranging from ~0.04 to 0.08, and it yields a reasonable match to the mean M*-V_2.2 relation. A model with m_d = 0.1 predicts overly strong correlations between disk size and M*-V_2.2 residual. Explaining the wide range of halo-to-disk mass ratios within 2.2R_d requires significant scatter in m_d values, with systematically lower m_d for galaxies with lower M* or lower stellar surface density Σ*.en_US
dc.publisherAmerican Astronomical Societyen_US
dc.subjectdark matteren_US
dc.subjectgalaxies: kinematics and dynamicsen_US
dc.subjectgalaxies: photometryen_US
dc.titleDark Matter and Stellar Mass in the Luminous Regions of Disk Galaxiesen_US

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