Circumnuclear Dust in Nearby Active and Inactive Galaxies. II. Bars, Nuclear Spirals, and the Fueling of Active Galactic Nuclei

We present a detailed study of the relation between circumnuclear dust morphology, host galaxy properties, and nuclear activity in nearby galaxies. We use our sample of 123 nearby galaxies with visible–near-infrared colormaps from the Hubble Space Telescope to create well-matched, “paired” samples of 28 active and 28 inactive galaxies, as well as 19 barred and 19 unbarred galaxies, that have the same host galaxy properties. Comparison of the barred and unbarred galaxies shows that grand design nuclear dust spirals are only found in galaxies with a large-scale bar. These nuclear dust spirals, which are present in approximately a third of all barred galaxies, also appear to be connected to the dust lanes along the leading edges of the large-scale bars. Grand design nuclear spirals are more common than inner rings, which are present in only a small minority of the barred galaxies. Tightly wound nuclear dust spirals, in contrast, show a strong tendency to avoid galaxies with large-scale bars. Comparison of the AGN and inactive samples shows that nuclear dust spirals, which may trace shocks and angular momentum dissipation in the ISM, occur with comparable frequency in both active and inactive galaxies. The only difference between the active and inactive galaxies is that several inactive galaxies appear to completely lack dust Based on observations with the NASA/ESA Hubble Space Telescope obtained at the the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. Carnegie Observatories, 813 Santa Barbara St., Pasadena, CA 91101-1292, [email protected], [email protected] Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, [email protected] Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, [email protected]