NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-03-21 T08:39:15 PDT
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For refcode 2011ApJ...727..130K:
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2011ApJ...727..130K Multi-wavelength Probes of Obscuration Toward the Narrow-line Region in Seyfert Galaxies Kraemer, S. B.; Schmitt, H. R.; Crenshaw, D. M.; Melendez, M.; Turner, T. J.; Guainazzi, M.; Mushotzky, R. F. Abstract. We present a study of reddening and absorption toward the narrow line regions (NLRs) in active galactic nuclei (AGNs) selected from the Revised Shapley-Ames, 12 micron, and Swift/Burst Alert Telescope samples. For the sources in host galaxies with inclinations of b/a > 0.5, we find that the mean ratio of [O III] {lambda}5007, from ground-based observations, and [O IV] 28.59 micron, from Spitzer/Infrared Spectrograph observations, is a factor of two lower in Seyfert 2s than Seyfert 1s. The combination of low [O III]/[O IV] and [O III] {lambda}4363/{lambda}5007 ratios in Seyfert 2s suggests more extinction of emission from the NLR than in Seyfert 1s. Similar column densities of dusty gas, N_H_~ several x 10^21^ cm^--2^, can account for the suppression of both [O III] {lambda}5007 and [O III] {lambda}4363, as compared to those observed in Seyfert 1s. Also, we find that the X-ray line O VII {lambda}22.1 A is weaker in Seyfert 2s, consistent with absorption by the same gas that reddens the optical emission. Using a Hubble Space Telescope/Space Telescope Imaging Spectrograph slitless spectrum of the Seyfert 1 galaxy NGC 4151, we estimate that only ~30% of the [O III] {lambda}5007 comes from within 30 pc of the central source, which is insufficient to account for the low [O III]/[O IV] ratios in Seyfert 2s. If Seyfert 2 galaxies have similar intrinsic [O III] spatial profiles, the external dusty gas must extend further out along the NLR, perhaps in the form of nuclear dust spirals that have been associated with fueling flows toward the AGN. Key words: galaxies: Seyfert
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