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Estimating the Number of Broad-Line Region Clouds

Published online by Cambridge University Press:  25 May 2016

M. Dietrich
M. Dietrich*
Affiliation:
Landessternwarte Heidelberg, Königstuhl, D-69117 Heidelberg, Germany

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The observed emission-line spectrum of active galactic nuclei is consistent with cold dense gas photoionized by a central continuum source (cf. Ferland & Persson 1989). The estimate of the filling factor of the line-emitting region yields f˜10−6 only (cf. Osterbrock 1993) and motivated the picture of numerous clouds moving around a central black hole. Early estimates of the number of BLR clouds indicated a lower limit of 104 to 105 individual clouds (Capriotti et al. 1981; Atwood et al. 1982). Recently, Arav et al. (1998) estimated the number to be at least of the order of 107 discrete emitters. But the number and the nature of these clouds are still unknown.

Type
III. AGN Theory and Models
Information
Symposium - International Astronomical Union , Volume 194: Activity in Galaxies and Related Phenomena , 1999 , pp. 317 - 318
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

Arav, N., et al. 1998, MNRAS, 297, 990 CrossRefGoogle Scholar
Atwood, B., Baldwin, J.A., & Carswell, R.F. 1982, ApJ, 257, 559 CrossRefGoogle Scholar
Bottorff, M., et al. 1997, ApJ, 479, 200 CrossRefGoogle Scholar
Capriotti, E., Foltz, C., & Byard, P. 1981, ApJ, 245, 386 CrossRefGoogle Scholar
Davidson, K. & Netzer, H. 1979, in Rev.Mod.Phys., 51, 737 Google Scholar
Ferland, G.J. & Persson, S.E. 1989, ApJ, 347, 656 CrossRefGoogle Scholar
Gaskell, C.M. & Peterson, B.M. 1987, ApJS, 65, 1 Google Scholar
Osterbrock, D.E. 1993, ApJ, 404, 551 Google Scholar
Tonry, J. & Davis, M. 1979 AJ, 84, 1511 CrossRefGoogle Scholar