The Narrow-Line Region of NGC 4151: A Turbulent Cauldron

Abstract

We present the first results of the Hubble Space Telescope/Faint Object Camera long-slit spectroscopy of the inner 8" of the narrow-line region (NLR) of NGC 4151 at a spatial resolution of 0.029". The emission gas is characterized by an underlying general orderly behavior, consistent with galactic rotation, over which are superposed kinematically distinct and strongly localized emission structures. High-velocity components shifted up to about 1500 km s^-1 from the systemic velocity are seen, associated with individual clouds located preferentially along the edges of the radio knots. Off-nuclear blue continuum emission is also observed, associated with the brightest emission line clouds. Emission-line ratios such as [Ne III] λ3869/[O II] λ3727 and [O II] λ3727/Hβ are observed to vary substantially between individual clouds. We advance the general picture that, as in other Seyfert galaxies observed with HST (e.g., NGC 1068, Mrk 573), the interaction of the ambient gas with the radio jet strongly influences both the morphology and the physical conditions of the NLR.

Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.