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We have conducted an extensive X-ray spectral variability study of a sampleof 20 Compton-thin type II galaxies using broad band spectra from XMM-Newton,Chandra, and Suzaku. The aim is to study the variability of the neutralintrinsic X-ray obscuration along the line of sight and investigate theproperties and location of the dominant component of the X-ray-obscuring gas.The observations are sensitive to absorption columns of $N_{\rm H} \sim10^{20.5-24} {\rm cm^{-2}}$ of fully- and partially-covering neutral and/orlowly-ionized gas on timescales spanning days to well over a decade. Wedetected variability in the column density of the full-covering absorber in7/20 sources, on timescales of months-years, indicating a component ofcompact-scale X-ray-obscuring gas lying along the line of sight of each ofthese objects. Our results imply that torus models incorporating clouds oroverdense regions should account for line of sight column densities as low as$\sim$ a few $\times 10^{21}$ cm$^{-2}$. However, 13/20 sources yielded nodetection of significant variability in the full-covering obscurer, with upperlimits to ${\Delta}N_{\rm H}$ spanning $10^{21-23}$ cm$^{-2}$. The dominantabsorbing media in these systems could be distant, such as kpc-scale dustystructures associated with the host galaxy, or a homogeneous medium along theline of sight. Thus, we find that overall, strong variability in full-coveringobscurers is not highly prevalent in Compton-thin type IIs, at least for oursample, in contrast to previous results in the literature. Finally, 11/20sources required a partial-covering, obscuring component in all or some oftheir observations, consistent with clumpy near-Compton-thick compact-scalegas.

The variable and non-variable X-ray absorbers in Compton-thin type-II Active Galactic Nuclei