On the Relationship Between the Optical Emission-Line and X-ray Luminosities in Seyfert 1 Galaxies

Abstract

We have explored the relationship between the [O III] $\lambda$5007 and the 2--10 keV luminosities for a sample of Broad- and Narrow-Line Seyfert 1 galaxies (BLSy1 and NLSy1, respectively). We find that both types of Seyferts span the same range in luminosity and possess similar [O III]/X-ray ratios. The NLSy1s are more luminous than BLSy1s, when normalized to their central black hole masses, which is attributed to higher mass accretion rates. However, we find no evidence for elevated [O III]/X-ray ratios in NLSy1s, which would have been expected if they had excess EUV continuum emission compared to BLSy1s. Also, other studies suggest that the gas in narrow-line regions (NLR) of NLSy1s and NLSy1s span a similar range in ionization, contrary to what is expected if those of the former are exposed to a stronger flux of EUV radiation. The simplest interpretation is that, like BLSy1s, a large EUV bump is not present in NLSy1s. However, we show that the [OIII]/X-ray ratio can be lowered as a result of absorption of the ionizing continuum by gas close to the central source, although there is no evidence that intrinsic line-of-sight absorption is more common among NLSy1s, as would be expected if there were a larger amount of circumnuclear gas. Other possible explanations include: 1) anisotropic emission of the ionizing radiation, 2) higher gas densities in the NLR of NLSy1s, resulting in lower average ionization, or 3) the presence of strong winds in the the nuclei of NLSy1s which may drive off much of the gas in the narrow-line region, resulting in lower cover fraction and weaker [O III] emission.

arXiv comment18 pages, including 3 figures, 2 tables. Accepted for publication in The Astrophysical Journal

References in corpus (32)

• Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei: I. Comparing the Photoionization and Reverberation Techniques
• The Soft X-Ray Properties of a Complete Sample of Optically Selected Quasars II. Final Results
• ASCA Observations of Seyfert 1 galaxies: III. The Evidence for Absorption & Emission due to Photoionized Gas
• Intrinsic Absorption Lines in Seyfert 1 Galaxies. I. Ultraviolet Spectra from the Hubble Space Telescope
• Narrow Line Seyfert 1 Galaxies and the Evolution of Galaxies & Active Galaxies
• A spectrophotometric atlas of Narrow-Line Seyfert 1 galaxies
• A comparison of the hard ASCA spectral slopes of broad and narrow-line Seyfert 1 galaxies
• Searching for the Physical Drivers of the Eigenvector 1 Correlation Space
• On X-ray Variability in Seyfert Galaxies
• Black Holes and Hosts of Active and Quiescent Galaxies: I. The Black Hole-Bulge Relation revisited
• Black hole mass and velocity dispersion of narrow line region in active galactic nuclei and narrow line Seyfert 1 galaxies
• Extreme Slim Accretion Disks and Narrow Line Seyfert 1 Galaxies: the Nature of the soft X-ray Hump
• The correlation of line strength with luminosity and redshift from composite QSO spectra
• Resolved Spectra of the Narrow-Line Region in NGC 1068. III. Physical Conditions in the Emission-Line Gas
• Black hole masses from power density spectra: determinations and consequences
• Infrared spectroscopy of NGC4151: Probing the obscured ionizing AGN continuum
• STIS Longslit Spectroscopy of the Narrow-Line Region of NGC 4151. II. Physical Conditions along Position Angle 221 Degress
• The High-Ionization Nuclear Emission-Line Region of Seyfert Galaxies
• Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564. III. Optical Observations and the Optical--UV--X-ray Connection
• STIS Echelle Observations of the Seyfert Galaxy NGC 4151: Physical Conditions in the Ultraviolet Absorbers
• Is There a Metallicity--Luminosity Relationship in AGN? The Case of Narrow-Line Seyfert 1 Galaxies
• Variable UV Absorption in the Seyfert 1.5 Galaxy NGC 3516: The Case for Associated UV and X-ray Absorption
• Evidence for a Physically Compact Narrow-Line Region in the Seyfert 1 Galaxy NGC 5548
• What do the UV Spectra of Narrow-line Seyfert 1 Galaxies tell us about their BLR?
• The Spectral Energy Distribution and Emission-Line properties of the NLS1 Galaxy Arakelian 564
• Chandra Grating Spectroscopy of the Seyfert Galaxy Ton S180
• The Spectral Energy Distribution of the Seyfert galaxy Ton S180
• A Chandra HETGS observation of the Narrow-line Seyfert 1 galaxy Ark 564
• On The Reddening in X-ray Absorbed Seyfert 1 Galaxies
• The Effect of Intrinsic UV Absorbers on the Ionizing Continuum and Narrow Emission Line Ratios in Seyfert Galaxies
• The relation between the mid-infrared emission and Black Hole Mass in Active Galactic Nuclei: A direct way to probe black hole growth?

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