Multi-wavelength Selected Compton-thick AGNs in Chandra Deep Field-South
  Survey
  Even in deep X-ray surveys, Compton-thick active galactic nuclei (CT AGNs,
${\rm N_H} \geqslant 1.5~\times~10^{24}~{\rm cm}^{-2}$) are difficult to be
identified due to X-ray flux suppression and their complex spectral shape.
However, the study of CT AGNs is vital for understanding the rapid growth of
black holes and the origin of cosmic X-ray background. In the local universe,
the fraction of CT AGNs accounts for 30% of the whole AGN population. We may
expect a higher fraction of CT AGNs in deep X-ray surveys, however, only 10% of
AGNs have been identified as CT AGNs in the 7 Ms \textit{Chandra} Deep
Field-South (CDFS) survey. In this work, we select 51 AGNs with abundant
multi-wavelength data. Using the method of the mid-infrared (mid-IR) excess, we
select hitherto unknown 8 CT AGN candidates in our sample. Seven of these
candidates can confirm as CT AGN based on the multi-wavelength identification
approach, and a new CT AGN (XID 133) is identified through the mid-IR
diagnostics. We also discuss the X-ray origin of these eight CT AGNs and the
reason why their column densities were underestimated in previous studies. We
find that the multi-wavelength approaches of selecting CT AGNs are highly
efficient, provided the high quality of observational data. We also find that
CT AGNs have a higher Eddington ratio than non-CT AGNs, and that both CT AGNs
and non-CT AGNs show similar properties of host galaxies.
