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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 607372.0, MPI für Astronomie / Publikationen_mpia
Quantifying the anisotropy in the infrared emission of powerful active galactic nuclei
Authors:Hönig, S. F.; Leipski, C.; Antonucci, R.; Haas, M.
Date of Publication (YYYY-MM-DD):2011
Journal Abbrev.:The Astrophysical Journal
Issue / Number:1
Audience:Not Specified
Abstract / Description:We use rest-frame near- and mid-IR data of an isotropically selected sample of quasars and radio galaxies at 1.0 <= z <= 1.4, which have been published previously by Leipski et al., to study the wavelength-dependent anisotropy of the IR emission. For that we build average spectral energy distributions of the quasar subsample (= type 1 AGNs) and radio galaxies (= type 2 AGNs) from ~1 to 17 μm and plot the ratio of both average samples. From 2 to 8 μm rest-frame wavelengths the ratio gradually decreases from 20 to 2 with values around 3 in the 10 μm silicate feature. Longward of 12 μm, the ratio decreases further and shows some high degree of isotropy at 15 μm (ratio ~1.4). The results are consistent with upper limits derived from the X-ray/mid-IR correlation of local Seyfert galaxies. We find that the anisotropy in our high-luminosity radio-loud sample is smaller than in radio-quiet lower-luminosity active galactic nuclei (AGNs) which may be interpreted in the framework of a receding torus model with luminosity-dependent obscuration properties. It is also shown that the relatively small degree of anisotropy is consistent with clumpy torus models.
Free Keywords:galaxies: active; galaxies: high-redshift; galaxies: nuclei; infrared: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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