Bibcode
Ramos Almeida, C.; Martínez González, M.; Asensio Ramos, A.; Acosta Pulido, J.; Hönig, S.; Alonso-Herrero, A.; Tadhunter, C.; González-Martín, O.
Bibliographical reference
Active Galactic Nuclei: what's in a name? Proceedings of a conference held 27 June - 1 July, 2016 in Garching, id.52
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8
2016
Citations
0
Refereed citations
0
Description
The origin of the unification model for 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, and four Sy2s classified as NHBLR
based on previous data. We report >4sigma detections of a HBLR in 11
of these galaxies (73% of the sample). Our results confirm that at least
some NHBLRs were misclassified, bringing previous publications reporting
differences between HBLR and NHBLR objects into question. We detect
broad Ha and Hb components in polarized light for 9 targets, and just
broad Ha for the other two. We do not find any correlation between the
properties of the polarized spectra and the column densities measured
from the X-rays or torus inclination, but a larger sample is required to
confirm this.