Hostname: page-component-669899f699-chc8l Total loading time: 0 Render date: 2025-04-27T18:53:53.100Z Has data issue: false hasContentIssue false
  • English
  • Français

Studies of narrow emission lines in AGNs

Published online by Cambridge University Press:  19 July 2016

Alexei V. Filippenko
Alexei V. Filippenko*
Affiliation:
Department of Astronomy, University of California, Berkeley, CA 94720, USA

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Optical spectra having moderately high resolution (~ 2 — 5 Å) are being used to study the profiles of narrow emission lines in active galactic nuclei (AGNs). It is often found that forbidden lines associated with high critical densities for collisional deexcitation are the broadest. A good example is [O III] λ4363 [ne(crit) ≈ 3 × 107 cm−3], whose width can be more than twice that of [O III] λ5007 [ne(crit) ≈ 8 × 105 cm−3]. The tight correlation between line width and ne(crit) implies that a much larger range of densities (∼ 102 — 107 cm−3) must be present among clouds in the narrow-line region than was previously believed. At times there almost appears to be a continuity between the narrow- and broad-line regions. In some objects the dense, high-velocity clouds are optically thick to ionizing radiation, since they emit [O I] λ6300 as well as species of much higher ionization (such as [Ne V] λ3426). These results help eliminate several difficulties in photoionization models of LINERs. It may also be possible to use the observed line widths as probes of the gravitational potential in AGNs.

Type
III. Spectral Line Studies
Information
Symposium - International Astronomical Union , Volume 119: Quasars , 1986 , pp. 289 - 294
Copyright
Copyright © Reidel 1986 

References

Carswell, R. F., Baldwin, J. A., Atwood, B., and Phillips, M. M. 1984, Ap. J., 286, 464.CrossRefGoogle Scholar
Davidson, K., and Netzer, H. 1979, Rev. Mod. Phys., 51, 715.CrossRefGoogle Scholar
De Robertis, M. M., and Osterbrock, D. E. 1984, Ap. J., 286, 171.CrossRefGoogle Scholar
Filippenko, A. V. 1985, Ap. J., 289, 475 (F85).CrossRefGoogle Scholar
Filippenko, A. V., and Halpern, J. P. 1984, Ap. J., 285, 458 (FH84).CrossRefGoogle Scholar
Filippenko, A. V., and Sargent, W. L. W. 1985, Ap. J. Suppl., 57, 503.CrossRefGoogle Scholar
Filippenko, A. V., and Sargent, W. L. W. 1986, in Structure and Evolution of Active Galactic Nuclei, ed. Giuricin, G. et al. (Dordrecht: Reidel).Google Scholar
Fosbury, R. A. E., Mebold, U., Goss, W. M., and Dopita, M. A. 1978, M. N. R. A. S., 183, 549.CrossRefGoogle Scholar
Halpern, J. P. 1982, , Harvard University.Google Scholar
Halpern, J. P., and Steiner, J. E. 1983, Ap. J. (Letters), 269, L37.CrossRefGoogle Scholar
Heckman, T. M. 1980, Astr. Ap., 87, 152.Google Scholar
Koski, A. T. 1978, Ap. J., 223, 56.CrossRefGoogle Scholar
Koski, A. T., and Osterbrock, D. E. 1976, Ap. J. (Letters), 203, L49.CrossRefGoogle Scholar
Osterbrock, D. E. 1979, in Active Galactic Nuclei, ed. Hazard, C. and Mitton, S. (Cambridge: Cambridge University Press), p. 25.Google Scholar
Osterbrock, D. E., Koski, A. T., and Phillips, M. M. 1976, Ap. J., 206, 898.CrossRefGoogle Scholar
Péquignot, D. 1984, Astr. Ap., 131, 159.Google Scholar
Puetter, R. C. 1986, these proceedings.Google Scholar
Weedman, D. W. 1977, Ann. Rev. Astr. Ap., 15, 69.CrossRefGoogle Scholar