Spectral properties of the narrow-line region in Seyfert galaxies selected from the SDSS-DR7
Article first published online: 5 NOV 2012
© 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS
Monthly Notices of the Royal Astronomical Society
Volume 427, Issue 2, pages 1266–1283, 1 December 2012
How to Cite
Vaona, L., Ciroi, S., Di Mille, F., Cracco, V., La Mura, G. and Rafanelli, P. (2012), Spectral properties of the narrow-line region in Seyfert galaxies selected from the SDSS-DR7. Monthly Notices of the Royal Astronomical Society, 427: 1266–1283. doi: 10.1111/j.1365-2966.2012.22060.x
- Issue published online: 5 NOV 2012
- Article first published online: 5 NOV 2012
- Manuscript Accepted: 4 SEP 2012
- Manuscript Received: 4 SEP 2012
- Alfred P. Sloan Foundation
- National Science Foundation
- US Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max-Planck Society
- Higher Education Funding Council for England
- methods: statistical;
- techniques: spectroscopic;
- galaxies: Seyfert
Although the properties of the narrow-line region (NLR) of active galactic nuclei (AGN) have been deeply studied by many authors in the past three decades, many questions are still open. The main goal of this work is to explore the NLR of Seyfert galaxies by collecting a large statistical spectroscopic sample of Seyfert 2 and Intermediate-type Seyfert galaxies having a high signal-to-noise ratio in order to take advantage of a high number of emission lines to be accurately measured.
2153 Seyfert 2 and 521 Intermediate-type Seyfert spectra were selected from Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) with a diagnostic diagram based on the oxygen emission-line ratios. All the emission lines, broad components included, were measured by means of a self-developed code, after the subtraction of the stellar component. Physical parameters, such as internal reddening, ionization parameter, temperature, density, gas and stellar velocity dispersion were determined for each object. Furthermore, we estimated mass and radius of the NLR, kinetic energy of the ionized gas and black hole accretion rate.
From the emission-line analysis and the estimated physical properties, it appears that the NLR is similar in Seyfert 2 and Intermediate-Seyfert galaxies. The only differences, lower extinction, gas kinematics in general not dominated by the host galaxy gravitational potential and higher percentage of [O iii]λ5007 blue asymmetries in Intermediate-Seyfert, can be ascribed to an effect of inclination of our line of sight with respect to the torus axis.