Compton thick absorber in type 1 quasar 3C 345 revealed by Suzaku and
  Swift/BAT
  The archival data of 3C 345, a type 1 quasar at $z = 0.5928$, obtained with
Suzaku and Swift/BAT are analysed. Though previous studies of this source
applied only a simple broken power law model, a heavily obscuring material is
found to be required by considering Akaike information criteria. The
application of the numerical torus model by Murphy & Yaqoob (2009) surprisingly
reveals the existence of Compton thick type 2 nucleus with the line-of-sight
hydrogen column density of the torus of $N_{\rm H} = 10^{24.5}$ cm$^{-2}$ and
the inclination angle of $\theta_{\rm inc} = 90^{\circ}$. However, this model
fails to account for the Eddington ratio obtained with the optical observations
by Gu et al. (2001) and Shen et al. (2011), or requires the existence of a
supermassive black hole binary, which was suggested by Lobanov & Roland (2005),
thus this model is likely to be inappropriate for 3C 345. A partial covering
ionized absorber model which accounts for absorption in "hard excess" type 1
AGNs is also applied, and finds a Compton thick absorber with the column
density of $N_{\rm H} \simeq 10^{25}$ cm$^{-2}$, the ionization parameter of
$\log \xi \gtrsim 2$, and the covering fraction of $75\% \lesssim f_{c}
\lesssim 85\%$. Since this model obtains a black hole mass of $\log ( M_{\rm
BH} / M_{\odot} ) = 9.8$, which is consistent with the optical observation by
Gu et al. (2001), this model is likely to be the best-fitting model of this
source. The results suggest that 3C 345 is the most distant and most obscured
hard excess AGN at this time.
