The Photometric and Kinematic Structure of Face‐on Disk Galaxies. I. Sample Definition, Hα Integral Field Spectroscopy, and H i Line Widths

We present a survey of the photometric and kinematic properties of 39 nearby,nearly face-on disk galaxies. Our approach exploits echelle-resolutionintegral-field spectroscopy of the H-alpha regions, obtained with DensePak onthe WIYN 3.5m telescope Bench Spectrograph. This data is complemented by HIline-profiles observed with the Nancay radio telescope for 25 of these samplegalaxies. Twelve additional line-widths are available for sample galaxies fromthe literature. In this paper, we introduce the goals of this survey, definethe sample selection algorithm, and amass the integral field spectroscopic dataand HI line-widths. We establish spatially-integrated H-alpha line-widths forthe sample. We test the veracity of these spatially-integrated line profiles byconvolving narrow-band imaging data with velocity field information for one ofthe sample galaxies, PGC 38268, and also by comparing to HI line profiles. Wefind HI and H-alpha line profiles to be similar in width but different inshape, indicating we are observing different spatial distributions of ionizedand neutral gas in largely axisymmetric systems with flat outerrotation-curves. We also find vertical velocity dispersions of the ionized diskgas within several disk scale-lengths have a median value of 18 km/s and an 80%range of 12-26 km/s. This is only a factor of ~2 larger than what is observedfor neutral atomic and molecular gas. With standard assumptions for intrinsicand thermal broadening for H-alpha, this translates into a factor of threerange in turbulent velocities, between 8 and 25 km/s.Comment: 29 pages, 20 figures; accepted for publication in ApJ Supplement Serie