We demonstrate the luminosity dependence of the covering factor (CF) of active galactic nuclei (AGNs), based on AKARI mid-infrared all-sky survey catalog. Combining the AKARI with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 243 galaxies at 9 m and 255 galaxies at 18 m. We then identied 64 AGNs at 9 μm and 105 AGNs at 18 μm by their optical emission lines. Following that, we estimated the CF as the fraction of type 2 AGN in all AGNs. We found that the CF decreased with increasing 18 μm luminosity, regardless of the choice of type 2 AGN classification criteria.

ABSTRACT
1. THE IMPORTANCE OF THE DUST TORUS
2. SAMPLE SELECTION
3. LUMINOSITY FUNCTION OF VARIOUS TYPES OFGALAXIES AT 9 AND 18 μm
4. LUMINOSITY DEPENDENCE OF THE COVERINGFACTOR
REFERENCES

• Yoshiki Toba(Research Center for Space and Cosmic Evolution, Ehime University)
• Shinki Oyabu(Graduate School of Science, Nagoya University)
• Hideo Matsuhara(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)
• Daisuke Ishihara(Graduate School of Science, Nagoya University)
• Matt A. Malkan(Department of Physics and Astronomy, University of California)
• Takehiko Wada(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)
• Youichi Ohyama(Academia Sinica, Institute of Astronomy and Astrophysics)
• Hirokazu Kataza(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)
• Satoshi Takita(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)
• Chisato Yamauchi(Misato Observatory, 180 Matsugamine)