The Distribution of Mass in Spiral Galaxies

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AST-0307417BershadyThe PI will determine independently the mass distributions of the disk and halo components of nearby, face-on spiral galaxies through direct, kinematic measurements. Such determinations are central to testing galaxy formation models. The actual observations are Ha and stellar velocity fields and velocity dispersions out to several disk scale lengths. Face-on systems favorably project the vertical component of the velocity ellipsoid, which is directly related to the mass of a disk of a given scale-height. Stellar scale-heights are well estimated by linking detailed kinematic and photometric properties of edge-on and face-on samples. Recent developments in large-aperture, integral-field instrumentation by the P.I. now make possible the required medium resolution spectroscopy, and give the best opportunity to date to measure disk mass and total mass independently. These detailed studies of nearby galaxies provide a springboard for the later observation and interpretation of high redshift systems using 10m and future 30m-class telescopes.The research program includes graduate and undergraduate training in astronomical research, observation, data analysis and especially instrumentation, public lectures, infrastructure improvements for the WIYN 3.5m telescope, and international collaboration with South African and German researchers.