2007/11/28 by James Mullaney, James R. Mullaney, M. J. Ward +1 · 91 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Balmer series #Doubly ionized oxygen #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Ionization #Line (geometry) #Physics #Spectral line #Stellar, planetary, and galactic studies #Velocity dispersion #William Herschel Telescope #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2007.12777.x
published in Monthly Notices of the Royal Astronomical Society 385(1), 53-74 (Oxford University Press) · 24 pages, 13 figures, 5 tables, Accepted for publication in MNRAS
arxiv created 2007/11/28 · openalex publication_date 2008/02/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Based on a new spectroscopic sample observed using the William Herschel Telescope, we examine the kinematic properties of the various emission-line regions in narrow-line Seyfert 1 galaxies (NLS1s) by modelling their profiles using multiple component fits. We interpret these results by comparison with velocity components observed for different lines species covered in the same spectrum, and equivalent components measured in the spectra of some broad-line Seyfert 1s and a representative Seyfert 2 galaxy. We find that the fits to the Hα and Hβ line profiles in NLS1s require an additional broad (≳3000 km s−1) component that might correspond to a suppressed broad-line region (BLR) with similar kinematics to those of typical broad-line Seyfert 1s. From the profiles of the forbidden high-ionization lines (FHILs) in NLS1s, we find evidence that they appear to trace an ‘intermediate’ velocity region with kinematics between the standard broad and narrow-line regions. Weaker evidence of this region is also present in the profiles of the permitted Balmer lines. Finally, we note that despite having similar ionization potentials, the relative intensities of the highly ionized lines of [Fe x]λ6374 and [Fe xi]λ7892 show considerable dispersion from one galaxy to another. The interpretation of this requires further modelling, but suggests the possibility of using the ratio as a diagnostic to constrain the physical conditions of the FHIL emitting region and possibly the shape of the spectral energy distribution in the vicinity of 200 eV. This spectral region is very difficult to observe directly due to photoelectric absorption both in our Galaxy and intrinsic to the source.