Hostname: page-component-77c89778f8-vsgnj Total loading time: 0 Render date: 2024-07-22T19:28:34.688Z Has data issue: false hasContentIssue false
  • English
  • Français

Some Implications of Ultraviolet Observations of Quasars and Active Galaxies

Published online by Cambridge University Press:  14 August 2015

Arthur F. Davidsen
Arthur F. Davidsen*
Affiliation:
Department of Physics, The Johns Hopkins University, Baltimore, Maryland 21218, U.S.A.

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.

The problem of the order of magnitude discrepancy in the expected and observed ratios of the Lyman and Balmer lines in quasars and active galaxies is reviewed. Whereas early photoionization models for the emission line regions predicted F(Lα)/F(Hβ) ≳ 40, the observations give values for this ratio in the range 3–8. Attempts at explaining the observations have involved dust, both external and internal to the emission line regions, and improved treatments of the collisional processes and radiative transfer effects in dense (Ne ~ 1010 cm−3), optically thick clouds. None of the effects considered is, by itself, able to explain all the observations, and a combination of several of them is probably required.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 92: Objects of High Redshift , 1980 , pp. 235 - 245
Copyright
Copyright © Reidel 1980 

References

Baldwin, J. A.: 1977, Mon. Not. R. astr. Soc. 178, pp. 67P–74P Google Scholar
Baldwin, J., and Netzer, H.: 1978, Ap. J. 226, pp. 1–20.Google Scholar
Baldwin, J. A. et al.: 1978, Ap. J. 226, pp. L57–L59.Google Scholar
Boggess, A., et al.: 1979, Ap. J. (Letters) 230, pp. L131–L136.Google Scholar
Boksenberg, A., et al.: 1978, Nature 275, pp. 404–414.CrossRefGoogle Scholar
Brocklehurst, M.: 1971, Mon. Not. R. astr. Soc. 153, pp. 471–490.Google Scholar
Canfield, R. C., and Puetter, R. C.: 1979, preprint.Google Scholar
Chan, Y.-W.T., and Burbidge, E. M.: 1975, Ap. J. 198, pp. 45–55.Google Scholar
Code, A. D. et al.: 1976, Ap. J. 203, pp. 417–434.Google Scholar
Davidsen, A. F., and Hartig, G. F.: 1978, Proc. COSPAR/IAU Symposium on X-Ray Astronomy , Eds. Baity, W. A. and Peterson, L. E., Pergamon, N. Y. Google Scholar
Davidsen, A. F., Hartig, G. F., and Fastie, W. G.: 1977, Nature 269, pp. 203–206.Google Scholar
Davidson, K.: 1972, Ap. J. 171, pp. 213–231.Google Scholar
Ferland, G., and Netzer, H.: 1979, Ap. J. 229, pp. 274–290.Google Scholar
Ferland, G. J. et al.: 1979, Mon. Not. R. astr. Soc., pp. 65P–71P.Google Scholar
Grasdalen, G. L.: 1976, Ap. J. (Letters) 208, pp. L11–L12.Google Scholar
Hartig, G. F.: 1978, , Google Scholar
Hyland, A. R., Becklin, E. E., and Neugebauer, G.: 1978, Ap. J. (Letters) 220, pp. L73–L75.CrossRefGoogle Scholar
Krolik, J., and McKee, C.: 1978, Ap. J. Suppl. 37, pp. 459–483.Google Scholar
Kwan, J., and Krolik, J.: 1979, preprint.Google Scholar
London, R.: 1979, Ap. J. 228, pp. 8–12.CrossRefGoogle Scholar
MacAlpine, G. M.: 1972, Ap. J. 175, pp. 11–30.Google Scholar
Netzer, H., and Davidson, K.: 1979, Mon. Not. R. astr. Soc. 187, pp. 871–882.Google Scholar
Netzer, H., and Penston, M.: 1976, Mon. Not. R. astr. Soc. 174, pp. 319–325.Google Scholar
Oke, J. B. and Lauer, T. R.: 1979, Ap. J. 230, pp. 360–372.Google Scholar
Oke, J. B., and Zimmerman, B.: 1979, Ap. J. 231, pp. L13–L17.Google Scholar
Osterbrock, D. E., and Koski, A. T.: 1976, Mon. Not. R. astr. Soc. 176. pp. 61P–66P.Google Scholar
Peutter, R. C. et al.: 1978, Ap. J. (Letters) 226, pp. L53–L56.Google Scholar
Peutter, R. C., Smith, H. E., and Willner, S. P.: 1979, Ap. J. (Letters) 227, pp. L5–L7.Google Scholar
Phillips, M. M.: 1978, Ap. J. 226, pp. 736–752.Google Scholar
Shuder, J. M., and MacAlpine, G. M.: 1979, Ap. J. 230, pp. 348–359.Google Scholar
Soiffer, B. T. et al.: 1979, Ap. J. (Letters) 227, pp. L1–L3.Google Scholar
Wampler, E. J.: 1968, Ap., J. (Letters) 154, pp. L53–L56.Google Scholar
Wampler, E. J.: 1971, Ap. J. 164, pp. 1–9.Google Scholar
Wu, C.-C.: 1977, Ap. J. (Letters) 217, pp. L117–L120.Google Scholar