2004/02/29 by Karen M. Leighly, John R. Moore · 8 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Doubly ionized oxygen #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Hubble space telescope #Ionization #Line (geometry) #Photoionization #Physics #Space Telescope Imaging Spectrograph #Spectral line #astro-ph
paper · pdf · doi:10.1086/422088
published as Astrophys.J. 611 (2004) 107-124 · 26 pages, 10 figures, accepted for publication in ApJ with no changes
arxiv created 2004/04/11 · openalex publication_date 2004/08/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present Hubble Space Telescope ( HST ) Space Telescope Imaging Spectrograph observations of two extreme narrow-line Seyfert 1 galaxies (NLS1's), IRAS 13224-3809 and 1H 0707-495. The spectra are characterized by very blue continua; broad, strongly blueshifted high-ionization lines (including C IV and N V); and narrow, symmetric intermediate- (including C III], Si III], and Al III) and low-ionization (e.g., Mg II) lines centered at the rest wavelength. The emission-line profiles suggest that the high-ionization lines are produced in a wind and that the intermediate- and low-ionization lines are produced in low-velocity gas associated with the accretion disk or base of the wind. In this paper, we present the analysis of the spectra from these two objects; in a companion paper, we present photoionization analysis and a toy dynamical model for the wind. The highly asymmetric profile of C IV suggests that it is dominated by emission from the wind, so we develop a template for the wind from the C IV line. We model the bright emission lines in the spectra using a combination of this template and a narrow symmetric line centered at the rest wavelength. We also analyzed a comparison sample of Hubble Space Telescope spectra from 14 additional NLS1's and constructed a correlation matrix of emission-line and continuum properties. A number of strong correlations were observed, including several involving the asymmetry of the C IV line.