Hubble Space TelescopeImaging of the Circumnuclear Environments of the CfA Seyfert Galaxies: Nuclear Spirals and Fueling

We present archival Hubble Space Telescope images of the nuclear regions of43 of the 46 Seyfert galaxies found in the volume-limited,spectroscopically-complete CfA Redshift Survey sample. Using an improved methodof image contrast enhancement, we create detailed high-quality structure mapsthat allow us to study the distributions of dust, star clusters, andemission-line gas in the circumnuclear regions (100-1000 pc scales) and in theassociated host galaxy. Essentially all of these Seyfert galaxies havecircumnuclear dust structures with morphologies ranging from grand-designtwo-armed spirals to chaotic dusty disks. In most Seyferts there is a clearphysical connection between the nuclear dust spirals on hundreds of parsecscales and large-scale bars and spiral arms in the host galaxies proper. Theseconnections are particularly striking in the interacting and barred galaxies.Such structures are predicted by numerical simulations of gas flows in barredand interacting galaxies, and may be related to the fueling of AGN by matterinflow from the host galaxy disks. We see no significant differences in thecircumnuclear dust morphologies of Seyfert 1s and 2s, and very few Seyfert 2nuclei are obscured by large-scale dust structures in the host galaxies. IfSeyfert 2s are obscured Seyfert 1s, then the obscuration must occur on smallerscales than those probed by HST.