Tuesday, 03/12/13

Not much from this Tuesday, but this paper by Zhang et al. discusses the connection between MIR dust and the outflows from Seyfert-type galaxies. What was new to me, although not really in this paper is that MIR-emission in Seyferts is elongated in a polar direction near their nuclei, suggesting warm dust within outflowing material. Based upon signs like that, Zhang et al. look for correlations between the outflow properties based upon SDSS optical spectroscopy and the MIR emission.

Connection Between Mid-Infrared Emission Properties and Narrow Line Region Outflows in Type 1 Active Galactic Nuclei

Kai Zhang (1,2), Ting-Gui Wang (1), Lin Yan (3), Xiao-Bo Dong (1) ((1) Key Laboratory for Research in Galaxies and Cosmology, The University of Sciences and Technology of China, (2) Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, (3) Spitzer Science Center, California Institute of Technology)
(Submitted on 9 Mar 2013)

The location of warm dust producing the Mid-infrared (MIR) emission in Type 1 Active Galactic Nuclei (AGNs) is complex and not yet fully known. We explore this problem by studying how the MIR covering factor (CF_{MIR} =L_{MIR}/L_{bol}) correlates with the fundamental parameters of AGN accretion process (such as L_{bol}, black hole mass MBH, and Eddington ratio L/LEdd) and the properties of narrow emission lines (as represented by [O
III] 5007), using large data sets derived from the Sloan Digital Sky Spectroscopic Survey (SDSS) and the Wide Infrared Sky Survey (WISE). Firstly we find that the luminosity of the [O III] wing component (Lwing) correlates more tightly with the continuum luminosity (L5100) than the luminosity of the line core component (Lcore) does, which is in line with our previous conclusion that the wing component, generally blueshifted, originates from the polar outflows in the inner narrow-line region (NLR). We then find that the MIR CF shows the strongest correlation with Lwing/L_{bol} rather than with Lcore/L_{bol} or the above fundamental AGN parameters, and the correlation becomes stronger as the infrared wavelength increases. We also confirm the anti-correlations of CF_{MIR} with L_{bol} and MBH, and the lack of dependence of CF_{MIR} on the Eddington ratio. These results suggest that a large fraction of the warm dust producing MIR emission in AGNs is likely embedded in polar outflows in the NLR instead of in the torus.

Comments: 8 pages, 4 figures, 1 table, ApJ accepted
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); Galaxy Astrophysics (astro-ph.GA)
Cite as: arXiv:1303.2152 [astro-ph.CO]
(or arXiv:1303.2152v1 [astro-ph.CO] for this version)
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