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NMA Survey of CO and HCN Emission from Nearby Active Galaxies

Kotaro Kohno, Ryohei Kawabe, Baltasar Vila-Vilaro

astro-pharXiv:astro-ph/9902251

Abstract

High resolution (a few arcseconds) observations of CO(1-0) and HCN(1-0) emission from nearby Seyfert galaxies have been conducted with the Nobeyama Millimeter Array. Based on the observed CO distributions and kinematics,we suggest that a small scale (a few 100 pc - a few kpc) distortion of the underlying potential seems to be necessary for Seyfert activity, although it is not a sufficient condition. We also find that the Toomre's Q values in the centers of Seyfert galaxies tend to be larger than unity, indicating the circumnuclear molecular gas disks around Seyfert nuclei would be gravitationally stable. The HCN/CO integrated intensity ratios (RHCN/CO) range over an order of magnitude, from 0.086 to 0.6. The Seyfert galaxies with high RHCN/CO may have an extended (r ~ 100 pc scale) envelope of obscuring material. The presence of kpc scale jet/ outflow might be also related to the extremely high RHCN/CO.

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