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The extended narrow line region of NGC 4151. I. Emission line ratios and their implications
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1990 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 236, no 1, 53-6262 p.Article in journal (Refereed) Published
Abstract [en]

The paper presents the first results from long-slit spectra of the Seyfert galaxy NGC 4151 which give average diagnostic ratios of weak lines in the extended narrow line region (ENLR) of that galaxy and the first direct density measurement in an ENLR. These data confirm that the ENLR is kinematically undisturbed gas in the disc of the galaxy which is illuminated by an ionizing continuum stronger by a factor of 13 than a power law interpolated between observed ultraviolet and X-ray fluxes. Explanations of this apparent excess include a hot thermal continuum, time variations and an anisotropic radiation field. The authors give reasons for favouring anisotropy which might be caused by shadowing by a thick accretion disc or by relativistic beaming. Shadowing by a molecular torus is unlikely, given the absence of an infrared signal from the reradiated flux absorbed by any torus. Anisotropy would have important implications for the bolometric luminosity and nature of active galactic nuclei

Place, publisher, year, edition, pages
1990. Vol. 236, no 1, 53-6262 p.
Keyword [en]
Experimental/ astronomical spectra, galactic nuclei, interstellar matter, Seyfert galaxies, visible astronomical observations/ AD 1989 05 05 to 06, interstellar medium, extended narrow line region, NGC 4151, spectra, Seyfert galaxy, density, kinematically undisturbed gas, hot thermal continuum, time variations, anisotropic radiation field, shadowing, thick accretion disc, relativistic beaming, bolometric luminosity, active galactic nuclei, 315 to 695 nm/ A9850R Active and peculiar galaxies A9850E Galactic structure, content and morphology A9840B Interstellar matter A9580J Photographic region astronomical observations/ wavelength 3.15E-07 to 6.95E-07 m
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Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:uu:diva-197177ISI: 3732424OAI: oai:DiVA.org:uu-197177DiVA: diva2:611963
Available from: 2013-03-19 Created: 2013-03-18 Last updated: 2013-03-19

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