Hubble Space Telescope STIS Ultraviolet Spectral Evidence of Outflow in Extreme Narrow-Line Seyfert 1 Galaxies. II. Modeling and Interpretation

By K. Leighly. 2004

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We present modeling to explore the conditions of the broad-line-emitting gas in two extreme narrow-line Seyfert 1 galaxies, using the observational results described in the first paper of this series. Photoionization modeling using CLOUDY was conducted for the broad blueshifted wind lines and the narrow, symmetric, rest-wavelength-centered disk lines separately. A broad range of physical conditions was explored for the wind component, and a figure of merit was used to quantitatively evaluate the simulation results. Of the three minima in the figure-of-merit parameter space, we favor the solution characterized by an X-ray-weak continuum, elevated abundances, a small column density (log NH ≈ 21.4), a relatively high ionization parameter (log U ≈ -1.2 to -0.2), a wide range of densities (log n ≈ 7-11), and a covering fraction of ~0.15. The presence of low-ionization emission lines implies that the disk component is optically thick to the continuum, and the Si III]/C III] ratio implies a density of 1010-1010.25 cm-3. A low ionization parameter (log U = -3) is inferred for the intermediate-ionization lines, unless the continuum is "filtered" through the wind before illuminating the intermediate-line-emitting gas, in which case log U = -2.1. The location of the emission regions was inferred from the photoionization modeling and a simple "toy" dynamical model. A large black hole mass (1.3 × 108 M☉) radiating at 11% of the Eddington luminosity is consistent with the kinematics of both the disk and wind lines, and an emission radius of ~104 RS is inferred for both. We compare these results with previous work and discuss implications.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4875ac0ad583e401f7572dd4cb143c32f427c2c8

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Citations in the corpus

Physical Properties of 15 Quasars at z ≳ 6.5 (2017, background): “…broad emission lines, such as C IV, show significant shifts bluewards with respect to the systemic redshifts in quasars at low−redshift (e.g. Richards et al. 2002): this has been considered a signature of outflows and/or of an important wind component in quasars BLRs (e.g. Leighly 2004).”
A Systematic Analysis of Fe II Emission in Quasars: Evidence for Inflow to the Central Black Hole (2008, background): “Highionization lines such as C iv may be emitted from some kind of outflowing diskwind (e.g., Leighly&Moore 2004; Leighly 2004; Baskin & Laor 2005; Shang et al. 2007 and references therein), whereas low-ionization lines such as H are anchored to a more disklike configuration.”
What controls the C iv line profile in active galactic nuclei (2004, background): “Leighly (2004b) finds a significant correlation between the fraction of the C iv line flux at v 0 km s−1 and C iv EW and αox in their NLS1s sample.”
UNIFICATION OF LUMINOUS TYPE 1 QUASARS THROUGH C iv EMISSION (2010, methodology): “For objects that are relatively weaker in the X-ray, a strong radiation-line-driven wind can form and said wind will further reduce the hard X-ray flux that reaches the disk component as the wind will “filter” the continuum (Leighly 2004; Leighly & Casebeer 2007).”