First X-ray-Based Statistical Tests for Clumpy-Torus Models: Eclipse
  Events from 230 Years of Monitoring of Seyfert AGN
  We present an analysis of multi-timescale variability in line-of-sight X-ray
absorbing gas as a function of optical classification in a large sample of
Seyfert AGN to derive the first X-ray statistical constraints for clumpy-torus
models. We systematically search for discrete absorption events in the vast
archive of RXTE monitoring of dozens of nearby type I and Compton-thin type II
AGN. We are sensitive to discrete absorption events due to clouds of
full-covering, neutral or mildly ionized gas with columns >~ 10^(22-25) cm^-2
transiting the line of sight.
  We detect 12 eclipse events in 8 objects, roughly tripling the number
previously published from this archive. Peak column densities span ~ 4-26 x
10^22 cm^-2. Event durations span hours to months. The column density profile
for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a
cloud that is being tidally sheared.
  We infer the clouds' distances from the black hole to span ~0.3 -140 x 10^4
R_g. In seven objects, the clouds' distances are commensurate with the outer
portions of Broad Line Regions (BLR), or the inner regions of infrared-emitting
dusty tori. We discuss implications for cloud distributions in the context of
clumpy-torus models. The probability of observing a source undergoing an
absorption event, independent of constant absorption due to non-clumpy
material, is 0.006(+0.160,-0.003) for type Is and 0.110(+0.461,-0.071) for type
IIs.
