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Emission Line Studies of AGN

from III - The Broad Line Region: Variability and Structure

Published online by Cambridge University Press:  04 August 2010

Brian R. Espey
Affiliation:
Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260. USA
Andrew Robinson
Affiliation:
University of Cambridge
Roberto Juan Terlevich
Affiliation:
Royal Greenwich Observatory, Cambridge
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Summary

Abstract

The Hubble Space Telescope (HST) has been producing data from regularly scheduled observations for some time now. At this juncture, it is an appropriate time to review some of the areas where instruments such as the Faint Object Spectrograph (FOS), when coupled with ground-based data, may improve studies of Active Galactic Nuclei (AGN) and, hopefully, stir the imaginations of the theorists! We show examples of objects where the data indicate that the emission line properties of high- and low-luminosity objects are similar, lending support to relatively simple models in which the emission line regions of AGN scale homologously. We note, however, that the definition of what the ‘normal’ properties of AGN are rather than individual peculiarities will have to await complete samples of objects with data covering as large a wavelength range as possible.

Line Ratios.

It has become feasible in recent years to study the Balmer lines of high redshift QSOs in some detail and to determine velocity-resolved ratios such as those of Lyα/Hα – see, for example,. Even more recently, it has become possible to regularly obtain UV data with the HST and to perform more detailed analysis than was possible using IUE spectra. As an example, in Figure 1 we show a comparison between the Lyα/Hα line ratios in two radio-loud objects of similar linewidth and velocity shifts.

The 3C273 data are from [4] and the PKS 1448 – 232 are taken from [2].

Type
Chapter
Information
The Nature of Compact Objects in Active Galactic Nuclei
Proceedings of the 33rd Herstmonceux Conference, held in Cambridge, July 6-22, 1992
, pp. 244 - 247
Publisher: Cambridge University Press
Print publication year: 1994

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  • Emission Line Studies of AGN
    • By Brian R. Espey, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260. USA
  • Edited by Andrew Robinson, University of Cambridge, Roberto Juan Terlevich, Royal Greenwich Observatory, Cambridge
  • Book: The Nature of Compact Objects in Active Galactic Nuclei
  • Online publication: 04 August 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511564765.057
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  • Emission Line Studies of AGN
    • By Brian R. Espey, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260. USA
  • Edited by Andrew Robinson, University of Cambridge, Roberto Juan Terlevich, Royal Greenwich Observatory, Cambridge
  • Book: The Nature of Compact Objects in Active Galactic Nuclei
  • Online publication: 04 August 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511564765.057
Available formats
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Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Emission Line Studies of AGN
    • By Brian R. Espey, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260. USA
  • Edited by Andrew Robinson, University of Cambridge, Roberto Juan Terlevich, Royal Greenwich Observatory, Cambridge
  • Book: The Nature of Compact Objects in Active Galactic Nuclei
  • Online publication: 04 August 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511564765.057
Available formats
×