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Coronal Lines in Active Galactic Nuclei

Published online by Cambridge University Press:  12 April 2016

E. Oliva
E. Oliva*
Affiliation:
Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I–50125 Firenze, Italy

Abstract

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Recent observations show that the CLR is small (a few tens of parsecs), has large column densities (N ≈ 1022 cm−2), and lies close to and is probably photoionized by the AGN. Coronal lines give information on Ne, Mg, Si, S, Ca, and Fe abundances, on the dust content and dynamics of the CLR, and can be used to trace hidden AGN. If they are powered by photoionization, coronal lines could be used to reconstruct the AGN spectrum at 100-400 eV. However, a proper understanding of the results requires careful use of photoionization codes, since the ionization parameter at the inner face is probably meaningless for CLR models, and a reliable convergence of the ‘highly variable’ atomic parameters for coronal lines. A shock model for the CLR in NGC 1068 requires collisional ionization of ≥ 600 M⊙ yr−1 of dense (n > 104 cm −3) gas within a region no larger than 30 pc. Maintaining a shock-excited CLR for a reasonable time requires > 1010M⊙ of fuel, which must be continuously supplied to the CLR.

Type
VI. The Narrow-Line Regions and Beyond
Information
International Astronomical Union Colloquium , Volume 159: Emission Lines in Active Galaxies: New Methods and Techniques , 1997 , pp. 288 - 297
Copyright
Copyright © Astronomical Society of the Pacific 1997

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