BAT AGN Spectroscopic Survey--VIII. Type 1 AGN With Massive Absorbing
  Columns
  We explore the relationship between X-ray absorption and optical obscuration
within the BAT AGN Spectroscopic Survey (BASS) which has been collecting and
analyzing the optical and X-ray spectra for 641 hard X-ray selected ($E>14$
keV) active galactic nuclei (AGN). We use the deviation from a linear broad
H$\alpha$-to-X-ray relationship as an estimate of the maximum optical
obscuration towards the broad line region and compare the $A_{\rm V}$ to the
hydrogen column densities ($N_{\rm H}$) found through systematic modeling of
their X-ray spectra. We find that the inferred columns implied by $A_{\rm V}$
towards the broad line region (BLR) are often orders of magnitude less than the
columns measured towards the X-ray emitting region indicating a small scale
origin for the X-ray absorbing gas. After removing 30\% of Sy 1.9s that
potentially have been misclassified due to outflows, we find that 86\%
(164/190) of the Type 1 population (Sy 1--1.9) are X-ray unabsorbed as expected
based on a single obscuring structure. However, 14\% (26/190), of which 70\%
(18/26) are classified as Sy 1.9, are X-ray absorbed, suggesting the broad line
region itself is providing extra obscuration towards the X-ray corona. The
fraction of X-ray absorbed Type 1 AGN remains relatively constant with AGN
luminosity and Eddington ratio, indicating a stable broad line region covering
fraction.
