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C. Warner, F. Hamann (University of Florida), M. Dietrich (Georgia State University)
We analyze UV spectra for a large sample of 578 Active Galactic Nuclei and derive Eddington ratios, L/Ledd, from bolometric luminosities and emission line widths for each object in the sample. We include a sample of 26 Narrow-Line Seyfert 1s (NLS1s) for comparative analysis. The sample spans five orders of magnitude in supermassive black hole (SMBH) mass, seven orders of magnitude in luminosity, and a redshift range from 0 < z < 5. A large fraction of the objects have L/Ledd > 1, which might be explained by non-spherically symmetric accretion. Composite spectra sorted by L/Ledd show an unusual emission-line behavior: nearly constant peak heights and decreasing FWHMs with increasing L/Ledd. This is in marked contrast to the emission-line behaviors with luminosity, SMBH mass, and \ion{C}{4} FWHM, which clearly show trends analogous to the Baldwin Effect: decreasing line peaks and equivalent widths with increasing luminosity, SMBH mass, and FWHM. The origins of the unusual behavior with L/Ledd are not understood, but one implication of this behavior is that metallicity estimates based on trends in emission line ratios involving nitrogen show no trend with L/Ledd in the composite spectra created from different ranges in L/Ledd. The NLS1 composite exhibits many unusual behaviors. It generally does not fit the trends between emission line rest-frame equivalent widths and L/Ledd as defined by the L/Ledd composite spectra. It also shows an unusually high metallicity for its SMBH mass and luminosity. We investigate the unusual behaviors of the NLS1s and we propose that host galaxy mass, correlated with SMBH mass and AGN luminosity, is the fundamental parameter affecting BLR metallicities, but a secondary effect must be enhancing the metallicity in NLS1s.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.