Dusty torus formation by anisotropic radiative pressure feedback of
  active galactic nuclei
  The feedback by active galactic nuclei (AGNs) is significant for the
formation and evolution of galaxies. It has been realized that the radiative
pressure feedback could be an efficient mechanism due to the existence of dust.
In this Letter, we discuss the effect of anisotropic radiative pressure, which
is inevitable if the UV/optical emission arises from an accretion disk. The
distribution of dusty gas should be also anisotropic due to the influence of
the anisotropic disk radiation, i.e. the dust in the face-on direction of an
accretion disk can be blown out relatively more easily, whereas the dust can
survive in the edge-on direction. This result can explain the presence of some
obscured AGNs with high Eddington ratios and can also quantitatively reproduce
the observed decreasing fraction of type 2 AGNs with increasing luminosity. A
sequence of AGN formation and evolution is also proposed, within the context of
the formation, evolution and exhaustion of the dusty torus. Our model predicts
the existence of bright AGNs with dusty tori, but without broad line regions.
Finally we discuss the implications of the anisotropic radiation for the
calculations of luminosity functions and radiation efficiencies of AGNs.
