Scattered X-rays in Obscured Active Galactic Nuclei and their
  Implications for Geometrical Structure and Evolution
  We construct a new sample of 32 obscured active galactic nuclei (AGNs)
selected from the Second XMM-Newton Serendipitous Source Catalogue to
investigate their multiwavelength properties in relation to the "scattering
fraction", the ratio of the soft X-ray flux to the absorption-corrected direct
emission. The sample covers a broad range of the scattering fraction
(0.1%-10%). A quarter of the 32 AGNs have a very low scattering fraction
(smaller than 0.5%), which suggests that they are buried in a geometrically
thick torus with a very small opening angle. We investigate correlations
between the scattering fraction and multiwavelength properties. We find that
AGNs with a small scattering fraction tend to have low [O III]lambda5007/X-ray
luminosity ratios. This result agrees with the expectation that the extent of
the narrow-line region is small because of the small opening angle of the
torus. There is no significant correlation between scattering fraction and
far-infrared luminosity. This implies that a scale height of the torus is not
primarily determined by starburst activity. We also compare scattering fraction
with black hole mass or Eddington ratio and find a weak anti-correlation
between the Eddington ratio and scattering fraction. This implies that more
rapidly growing supermassive black holes tend to have thicker tori.
