Hubble Space Telescope Observations of the CfA Seyfert 2s: Near-infrared Surface Photometry and Nuclear Bars

摘要

We present near-infrared J and H surface photometry of 24 of the nearbySeyfert 1.8, 1.9 and 2 galaxies from the CfA Seyfert sample. The excellentangular resolution of HST probes spatial scales as small as tens of parsecs inmost of these AGN and is sensitive to the presence of nuclear bars and otherpotential signatures of the AGN fueling process that channels host galaxy gasand dust to the nuclear region. We have used elliptical isophote techniques tosearch for nuclear bars in all of these galaxies and have employed atwo-dimensional fitting technique to model the nuclear point source and surfacebrightness distribution of a bright subsample of these galaxies in an attemptto alleviate the impact of the nuclear point source on our sensitivity tonuclear bars. We find stellar nuclear bar candidates in four of these galaxies:Mrk 471, Mrk 270, Mrk 573, and NGC 5929, nearly 20% of the total sample. Thepercentage rises to ~30% when systems with disturbed morphologies or highinclinations are excluded. The nuclear bars in Mrk 573 and Mrk 270 exhibit someevidence for dust lanes along their leading edges, analogous to the structuresseen in host galaxy bars, while the dust lanes in Mrk 471 and NGC 5929 exhibita more complex morphology. The fact that most of these AGN do not appear tocontain stellar nuclear bars suggests that they are not the fueling mechanismfor most low-luminosity AGN.