Modeling the Mass Distribution in Spiral Galaxies
Session 25 -- Ellipticals and Dark Matter
Oral presentation, Monday, 9, 1995, 10:00am - 11:30am

## [25.06] Modeling the Mass Distribution in Spiral Galaxies

A.H. Broeils (Cornell), S. Courteau (NOAO/KPNO)

We present mass models for a sample of 294 Sb-Sc spiral galaxies drawn from Courteau's Northern Tully-Fisher compilation (Courteau 1992). This sample includes 327 Sb-Sc galaxies with optical (H$\alpha$ and [NII]) rotation curves and deep r-band CCD surface photometry. By its nature, this sample is ideally suited for mass modeling study.

The purpose of the present study is to establish global trends in the properties of luminous and dark matter with galactic parameters by matching the expected rotation curve, calculated from the observed luminosity profile, with the observed rotation curves under the assumption of constant mass-to-light ratio with radius. We present various techniques for decomposing the surface brightness profile into bulge and disk profiles with a discussion of their effects on final mass models. The relevance of bulge/disk decomposition on maximum-disk M/L ratios and preferred choice of bulge profile ($R^{1/4}$, Hernquist, exponential or unrestricted) is also examined. Finally, we discuss the distribution of r-band maximum-disk M/L ratios and correlations with other galactic properties.