A direct comparison of X-ray spectral models for tori in active galactic
  nuclei
  Several X-ray spectral models for tori in active galactic nuclei (AGNs) are
available to constrain the properties of tori; however, the accuracy of these
models has not been verified. We recently construct a code for the torus using
Geant4, which can easily handle different geometries (Liu & Li 2014). Thus, we
adopt the same assumptions as Murphy & Yaqoob (2009, hereafter MY09) and
Brightman & Nandra (2011, hereafter BN11) and try to reproduce their spectra.
As a result, we can reproduce well the reflection spectra and the strength of
the Fe K$\alpha$ line of MY09, for both $\NH=10^{24}$ and $10^{25}$ cm$^{-2}$.
However, we cannot produce the strong reflection component of BN11 in the
low-energy band. The origin of this component is the reflection from the
visible inner wall of the torus, and it should be very weak in the edge-on
directions under the geometry of BN11. Therefore, the behaviour of the
reflection spectra in BN11 is not consistent with their geometry. The strength
of the Fe K$\alpha$ line of BN11 is also different from our results and the
analytical result in the optically thin case. The limitation of the spectral
model will bias the parameters from X-ray spectral fitting.
