X-ray absorption variability in NGC 4507
  We present a complete spectral analysis of an XMM-Newton and Chandra campaign
of the obscured AGN in NGC 4507, consisting of six observations spanning a
period of six months, ranging from June 2010 to December 2010. We detect strong
absorption variability on time scales between 1.5 and 4 months, suggesting that
the obscuring material consists of gas clouds at parsec-scale distance. The
lack of significant variability on shorter time scales suggests that this event
is not due to absorption by broad line region clouds, which was instead found
in other studies of similar sources. This shows that a single, universal
structure of the absorber (either BLR clouds, or the parsec-scale torus) is not
enough to reproduce the observed complexity of the X-ray absorption features of
this AGN.
