Hubble Space Telescope Spectroscopic Observations of the Narrow-Line Region in Nearby Low-Luminosity Active Galactic Nuclei - AstrophysicsReport as inadecuate




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Abstract: Abridged We present STIS observations of 14 nearby low-luminosity activegalactic nuclei, including 13 LINERs and 1 Seyfert, taken at multiple parallelslit positions centered on the galaxy nuclei and covering the H-alpha spectralregion. For each galaxy, we measure the emission-line velocities, line widths,and strengths, to map out the inner narrow-line region structure. There is awide diversity among the velocity fields: in a few galaxies the gas is clearlyin disk-like rotation, while in other galaxies the gas kinematics appearchaotic or are dominated by radial flows with multiple velocity components. TheS II line ratio indicates a radial stratification in gas density, with asharp increase within the inner 10-20 pc, in the majority of the Type 1objects. We examine how the N II 6583 line width varies as a function ofaperture size over a range of spatial scales, extending from scales comparableto the black hole-s sphere of influence to scales dominated by the hostgalaxy-s bulge. For most galaxies in the sample, we find that the emission-linevelocity dispersion is largest within the black hole-s gravitational sphere ofinfluence, and decreases with increasing aperture size toward values similar tothe bulge stellar velocity dispersion measured within ground-based apertures.Future dynamical modeling in order to determine black hole masses for a fewobjects in this sample may be worthwhile, although disorganized motion willlimit the accuracy of the mass measurements.



Author: Jonelle L. Walsh, Aaron J. Barth, Luis C. Ho, Alexei V. Filippenko, Hans-Walter Rix, Joseph C. Shields, Marc Sarzi, Wallace L. W.

Source: https://arxiv.org/







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