Detalles de publicación

PP 016038

Upholding the Unified Model for Active Galactic Nuclei: VLT/FORS2 Spectropolarimetry of Seyfert 2 galaxies

Cristina Ramos Almeida(1,2), M. J. Martínez Gonzalez(1,2), A. Asensio Ramos(1,2), J. A. Acosta-Pulido(1,2), et al.
(1) IAC, (2) ULL
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.

 
Aceptado para publicación en MNRAS | Enviado el 2016-06-08 | Proyecto P/301027/01, P/301508