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Implications of Nonlinear Line Response in Variable Seyfert Nuclei

Published online by Cambridge University Press:  19 July 2016

Joseph C. Shields ,
Gary J. Ferland  and
Bradley M. Peterson
Joseph C. Shields
Affiliation:
Steward Observatory, University of Arizona
Gary J. Ferland
Affiliation:
Department of Physics & Astronomy, University of Kentucky
Bradley M. Peterson
Affiliation:
Department of Astronomy, Ohio State University

Extract

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Variable Seyfert nuclei exhibit correlations between emission-line and continuum luminosity consistent with photoionization, although the emission lines (including recombination features such as Lyα) tend to respond nonlinearly to changes in the continuum. A nonlinear response will result if some of the broad-line region (BLR) clouds become fully ionized in hydrogen, such that their emission measure does not then vary in proportion to the incident continuum flux. For thin clouds, emission in transitions from heavy elements may grow or decline with increasing incident flux, reflecting changes in the ionization structure of the cloud. Direct evidence for a fully ionized component within the BLR is provided by correlation analysis of ultraviolet line response in NGC 5548 (Sparke, 1993).

Type
Poster Contributions: Line Studies
Information
Symposium - International Astronomical Union , Volume 159: Multi-Wavelength Continuum Emission of AGN , 1994 , pp. 459
Copyright
Copyright © Kluwer 1994 

References

Clavel, J., et al. 1992, ApJ , 393, 113 Google Scholar
Shields, J. C., & Ferland, G. J. 1993, ApJ , 402, 425 Google Scholar
Sparke, L. S. 1993, ApJ , 404, 570 Google Scholar