Modeling the Mass Distribution in Spiral Galaxies
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We use deep r-band photometry and Halpha rotation curves for a sample of 290 late-type spirals to model their mass distribution within the optical radius. We examine luminosity profile decompositions into bulge and disk carefully and confirm that bulge light is best modeled by a seeing-convolved exponential profile. The optical rotation curves are well-reproduced with a combination of bulge and "maximum" disk components only. No dark halo is needed. The disk mass-to-light ratios (M/L's) correlate with the "size" of galaxies, as measured by mass, luminosity, or disk scale length. Correcting for this scale effect yields a narrow distribution of intrinsic M/L's for this galaxy population. By combining these models with HI data for other samples, we confirm that the luminous mass fraction increases with galaxy "size".
8 pages LaTeX, including 5 figures. Uses paspconf.sty, epsf.sty and natbib209.sty. To appear in "Dark and Visible Matter in Galaxies and Cosmological Implications", eds. M. Persic and P. Salucci, A.S.P. Conference Series. 1997
8 pages LaTeX, including 5 figures. Uses paspconf.sty, epsf.sty and natbib209.sty. To appear in "Dark and Visible Matter in Galaxies and Cosmological Implications", eds. M. Persic and P. Salucci, A.S.P. Conference Series. 1997