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The Korean Astronomical Society (한국천문학회)
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AKARI OBSERVATIONS OF DUSTY TORI OF ACTIVE GALACTIC NUCLEI

  • Oyabu, Shinki (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Kaneda, Hidehiro (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Izuhara, Masaya (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Tomita, Keisuke (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Ishihara, Daisuke (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Kawara, Kimiaki (Institute of Astronomy, the University of Tokyo) ;
  • Matsuoka, Yoshiki (National Astronomical Observatory of Japan)
  • Received : 2016.02.20
  • Accepted : 2016.10.20
  • Published : 2017.03.31
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Abstract

The dusty torus of Active Galactic Nuclei (AGNs) is one of the important components for the unification theory of AGNs. The geometry and properties of the dusty torus are key factors in understanding the nature of AGNs as well as the formation and evolution of AGNs. However, they are still under discussion. Infrared observation is useful for understanding the dusty torus as thermal emission from hot dust with the dust sublimation temperature (~ 1500 K) has been observed in the infrared. We have analyzed infrared spectroscopic data of low-redshift and high-redshift quasars, which are luminous AGNs. For the low-redshift quasars, we constructed the spectral energy distributions (SEDs) with AKARI near-infrared and Spitzer mid-infrared spectra and decomposed the SEDs into a power-law component from the nuclei, silicate features, and blackbody components with different temperatures from the dusty torus. From the decomposition, the temperature of the innermost dusty torus shows the range between 900-2000 K. For the high-redshift quasars, AKARI traced rest-frame optical and near-infrared spectra of AGNs. Combining with WISE data, we have found that the temperature of the innermost dusty torus in high redshift quasars is lower than that in typical quasars. The hydrogen $H{\alpha}$ emission line from the braod emission line region in the quasars also shows narrow full width at half maximum of $3000-4000km\;s^{-1}$. These results indicate that the dusty torus and the broad emission line region are more extended than those of typical quasars.

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References

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