NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2018-12-16 T09:04:27 PST
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For refcode 2006A&A...459...55B:
Retrieve 6 NED objects in this reference.
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NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
2006A&A...459...55B Size and properties of the narrow-line region in Seyfert-1 galaxies from spatially-resolved optical spectroscopy Bennert, N.; Jungwiert, B.; Komossa, S.; Haas, M.; Chini, R. Abstract. Context: Spatially resolved emission-line spectroscopy is a powerful tool for determining the physical conditions in the narrow-line region (NLR) of active galactic nuclei (AGNs). We recently used optical long-slit spectroscopy to study the NLRs of a sample of six Seyfert-2 galaxies. We have shown that such an approach, in comparison to the commonly used [O III] narrow-band imaging alone, allows us to probe the size of the NLR in terms of AGN photoionisation. Moreover, several physical parameters of the NLR can be directly accessed. Aims: We here apply the same methods to study the NLR of six Seyfert-1 galaxies and compare our results to those of Seyfert-2 galaxies. Methods: We employ diagnostically valuable emission-line ratios to determine the physical properties of the NLR, including the core values and radial dependencies of density, ionisation parameter, and reddening. Tracking the radial change of emission-line ratios in diagnostic diagrams allows us to measure the transition between AGN-like and H II-like line excitation, and thus to measure the size of the NLR. Results: In the diagnostic diagrams, we find a transition between line ratios falling in the AGN regime and those typical of H II regions in two Seyfert-1 galaxies, thereby determining the size of the NLR. The central electron temperature and ionisation parameter are, in general, higher in type-1 Seyferts than in type 2s. In almost all cases, both electron density and ionisation parameter decrease with radius and the decrease is faster in Seyfert-1 galaxies than in Sy2s. In several objects, the gaseous velocity distribution is characteristic of rotational motion in an (inclined) emission-line disk in the centre. We give estimates of the black-hole masses and discuss our findings in detail for each object. Key words: galaxies: active, galaxies: nuclei, galaxies: Seyfert
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