Relationship between Gamma-ray loudness and X-ray spectra of Radio
  Galaxies
  The {\it Fermi} satellite has detected $\sim$60 radio galaxies (RGs). In this
study, we investigate the difference in the properties of X-ray spectra between
GeV-loud RGs and GeV-quiet RGs. Our sample comprises 68 objects: 36 RGs
detected with {\it Fermi} and 32 RGs not detected with gamma rays. We analyzed
the X-ray spectra of these 68 objects using data from the {\it XMM-Newton},
{\it Chandra}, {\it NuSTAR}, and {\it Swift} satellites. Our results show that
most GeV-loud RGs do not exhibit significant absorption, while $\sim$50\% of
the GeV-quiet RGs exhibit significant absorption. This suggests that the jet of
GeV-loud RGs is viewed from a small angle, and thus the emission is not easily
blocked by the torus. Moreover, we reported that RGs with a heavy absorption
are mostly in the X-ray luminosity range of $10^{43}-10^{45}$erg s$^{-1}$;
however, few RGs with lower and higher luminosity suffer from heavy absorption.
This is the same trend as that of Seyfert galaxies.
