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D.M. Crenshaw (GSU), S.B. Kraemer (CUA)
We present a study of Hubble Space Telescope archival images of Seyfert 1 galaxies, obtained through large bandpasses in the optical with the WFPC2. We find that the incidence of large stellar bars (on kiloparsec scales) is much higher in narrow-line Seyfert 1s (NLS1s) than in broad-line Seyfert 1s (BLS1s). In particular, the percentage of Seyfert 1 galaxies that shows bars declines steadily from ~100% for those whose broad H\beta lines have a full-width at half-maximum (FWHM) \approx 500 km s-1 to ~25% for FWHM \approx 2000 km s-1, and remains approximately constant at higher FWHM. This result suggests a link between the properties of the host galaxies and those of the active nuclei in NLS1s. The current paradigm for NLS1s is that they have much higher accretion rates than BLS1s. The stellar bars represent an efficient means for transporting large amounts of gas (i.e., fuel) to the circumnuclear regions (at distances \leq 100 pc from the nuclei) to support the high accretion rates.
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.