A New Sample of Buried Active Galactic Nuclei Selected from the Second
  XMM-Newton Serendipitous Source Catalogue
  We present the results of X-ray spectral analysis of 22 active galactic
nuclei (AGNs) with a small scattering fraction selected from the Second
XMM-Newton Serendipitous Source Catalogue using hardness ratios. They are
candidates of buried AGNs, since a scattering fraction, which is a fraction of
scattered emission by the circumnuclear photoionized gas with respect to direct
emission, can be used to estimate the size of the opening part of an obscuring
torus. Their X-ray spectra are modeled by a combination of a power law with a
photon index of 1.5-2 absorbed by a column density of 10^23-24 cm^-2, an
unabsorbed power law, narrow Gaussian lines, and some additional soft
components. We find that scattering fractions of 20 among 22 objects are less
than a typical value (3%) for Seyfert2s observed so far. In particular, those
of eight objects are smaller than 0.5%, which are in the range for buried AGNs
found in recent hard X-ray surveys. Moreover, [O III] lambda5007 luminosities
at given X-ray luminosities for some objects are smaller than those for
Seyfert2s previously known. This fact could be interpreted as a smaller size of
optical narrow emission line regions produced in the opening direction of the
obscuring torus. These results indicate that they are strong candidates for the
AGN buried in a very geometrically thick torus.
