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Excitation Mechanisms in Seyfert Galaxies

Published online by Cambridge University Press:  12 April 2016

M.G. Allen
Affiliation:
Mt. Stromlo and Siding Spring Observatories, Private Bag, Weston Creek P.O., ACT 2611, Australia
M.A. Dopita
Affiliation:
Mt. Stromlo and Siding Spring Observatories, Private Bag, Weston Creek P.O., ACT 2611, Australia
Z. I. Tsvetanov
Affiliation:
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA

Extract

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The excitation mechanism of the extended emission-line regions (EELRs) in Seyfert galaxies is commonly thought to be nuclear photoionization. However, some Seyfert galaxies have EELRs with disturbed kinematics, outflows, and morphology which is indicative of interaction between radio plasma and the ISM of the host galaxy. In these cases shock excitation must also be considered (BickneU 1993).

To investigate the importance of shocks and photoionization, we have taken two approaches: mapping the spatial dependence of the line ratios, and using UV line ratios which are sensitive discriminants between shocks and photoionization.

Type
VII. Shocks and Photoionization
Copyright
Copyright © Astronomical Society of the Pacific 1997

References

Bicknell, G.V. 1993, in The Physics of Active Galactic Nuclei, ed. Bicknell, , Dopita, , & Quinn, , ASP Conf. Ser. 54, p. 231.Google Scholar
Dopita, M.A., & Sutherland, R.S. 1995, ApJ, 455, 468.Google Scholar