Upholding the Unified Model for Active Galactic Nuclei: VLT/FORS2
  Spectropolarimetry of Seyfert 2 galaxies
  The origin of the unification model for Active Galactic Nuclei (AGN) was the
detection of broad hydrogen recombination lines in the optical polarized
spectrum of the Seyfert 2 galaxy (Sy2) NGC 1068. Since then, a search for the
hidden broad-line region (HBLR) of nearby Sy2s started, but polarized broad
lines have only been detected in 30-40% of the nearby Sy2s observed to date.
Here we present new VLT/FORS2 optical spectropolarimetry of a sample of 15
Sy2s, including Compton-thin and Compton-thick sources. The sample includes six
galaxies without previously published spectropolarimetry, some of them normally
treated as non-hidden BLR (NHBLR) objects in the literature, four classified as
NHBLR, and five as HBLR based on previous data. We report >=4{\sigma}
detections of a HBLR in 11 of these galaxies (73% of the sample) and a
tentative detection in NGC 5793, which is Compton-thick according to the
analysis of X-ray data performed here. Our results confirm that at least some
NHBLRs are misclassified, bringing previous publications reporting differences
between HBLR and NHBLR objects into question. We detect broad H{\alpha} and
H{\beta} components in polarized light for 10 targets, and just broad H{\alpha}
for NGC 5793 and NGC 6300, with line widths ranging between 2100 and 9600 km/s.
High bolometric luminosities and low column densities are associated with
higher polarization degrees, but not necessarily with the detection of the
scattered broad components.
