NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-18 T18:46:25 PDT
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For refcode 2011A&A...536A..78K:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2011A&A...536A..78K Mapping the radial structure of AGN tori Kishimoto, M.; Honig, S. F.; Antonucci, R.; Millour, F.; Tristram, K. R. W.; Weigelt, G. Abstract. We present mid-IR interferometric observations of six type 1 AGNs at multiple baseline lengths ranging from 27 m to 130 m, reaching high angular resolutions up to lambda/B ~ 0.02 arcsec. For two of the targets, we have simultaneous near-IR interferometric measurements as well, taken within a week. We find that all the objects are partially resolved at long baselines in these IR wavelengths. The multiple-baseline data directly probe the radial distribution of the material on sub-pc scales. We show that for our sample, which is small but spans over ~2.5 orders of magnitudes in the UV/optical luminosity L of the central engine, the radial distribution clearly and systematically changes with luminosity. The brightness distribution at a given mid-IR wavelength seems to be rather well described by a power law, which makes a simple Gaussian or ring size estimation quite inadequate. In this case, a half-light radius R_1/2_ can be used as a representative size. We show that the higher luminosity objects become more compact in normalized half-light radii R_1/2_/R_in_ in the mid-IR, where R_in_ is the dust sublimation radius empirically given by the L^1/2^ fit of the near-IR reverberation radii. This means that, contrary to previous studies, the physical mid-IR emission size (e.g. in pc) is not proportional to L^1/2^, but increases with L much more slowly. With our current datasets, we find that R_1/2_ is proportional to L^0.21 +/- 0.05^ at 8.5 micron, and R_1/2_ nearly constant at 13 micron. The derived size information also seems to correlate with the properties of the total flux spectrum, in particular the smaller R_1/2_/R_in_ objects having bluer mid-IR spectral shape. We use a power-law temperature/density gradient model as a reference, and infer that the radial surface density distribution of the heated dust grains at a radius r changes from a steep ~r^-1^ structure in high luminosity objects to a shallower ~r^0^ structure in those of lower luminosity. The inward dust temperature distribution does not seem to smoothly reach the sublimation temperature - on the innermost scale of ~R_in_, a relatively low temperature core seems to co-exist with a slightly distinct brightness concentration emitting roughly at the sublimation temperature. Appendices are available in electronic form at http://www.aanda.org Key words: galaxies: active, galaxies: Seyfert, infrared:, galaxies, techniques: interferometric
Retrieve 6 NED objects in this reference.
Please click here for ADS abstract

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