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Structure and Nature of AGNs

Published online by Cambridge University Press:  07 August 2017

Hagai Netzer
Hagai Netzer*
Affiliation:
School of Physics and Astronomy and The Wise Observatory, Tel Aviv University, Tel Aviv 69978, Israel

Abstract

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This review discusses the present understanding of the inner region of AGN. Several fundamental questions are adressed, such as the determination of the central mass, the accretion rate and the presence or absence of massive accretion disks. The “standard model”, used until recently to deduce the density, ionization, geometry and other physical properties of AGN, is facing sever difficulties and several unsolved problems, such as the hydrogen line ratio, the FeII spectrum, the energy budget discrepency and the confinement of the broad line clouds may force us to abandon it all together. The new line-continuum reverberation measurements are perhaps the most important developement of recent years and their significance is discussed in relation to the other mentioned problems. Thin or thick accretion disks are likely to be present in the very center of AGNs. The theory of such disks is not advanced enough to provide accurate spectral calculations and the best way to identify them is to look for the signature of their nonisotropic radiation field in well selected samples. Several new developements and ideas, such as disk shaped emission line region, stars and stellar winds as broad line clouds, dust emission and very small-very dense BLR are also discussed.

Type
Part 2: BLR and Variability
Information
Symposium - International Astronomical Union , Volume 134: Active Galactic Nuclei , 1989 , pp. 69 - 84
Copyright
Copyright © Kluwer 1989 

References

Averett, E.H. and Loeser, R., 1988, Ap.J., 331, 211.Google Scholar
Baldwin, J.A., 1977a, MNRAS, 178, 67p.Google Scholar
Baldwin, J.A., 1977b, Ap.J., 266, 1.Google Scholar
Baldwin, J.A., Wampler, J.E., nd Gaskell, C.M., 1988, Ap.J (in press) Google Scholar
Bechtold, J., Green, R.F., Weymann, R.J., Schmidt, M., Estabrook, F.B., Sherman, R.D., Wahlquist, H and Heckman, T., 1984, Ap.J., 281, 76.Google Scholar
Bechtold, J., Czerny, B., Elvis, M., Fabbiano, G., and Green, R.F., 1987, Ap.J., 314, 699.Google Scholar
Begelman, M.C., 1985, in Astrophysics Of Active Galaxies and QSOs, (Miller, J. ed.), p411.Google Scholar
Barvainis, R., 1987, Ap.J., 320, 537.Google Scholar
Chen, K., Halpern, J.P., and Filippenko, A.V., 1988 (preprint) Google Scholar
Clavel, J., Wamsteker, W., and Glass, I, 1988 (preprint) Google Scholar
Collin-Souffrin, S., 1986, Astr.Ap. 166, 115.Google Scholar
Collin-Souffrin, S., Dyson, J.E., McDowell, J.C., and Perry, J.J., 1988, MNRAS, 232, 539.Google Scholar
Collin-Souffrin, S. and Dumont, S., 1986, Astr.Ap., 166, 13.Google Scholar
Czerny, B, and Elvis, M., 1987, Ap.J., 312, 325.Google Scholar
Cunningham, C.T., 1975, Ap.J., 202, 788.Google Scholar
Davidson, K., 1972, Ap.J., 171, 213.Google Scholar
Davidson, K., and Netzer, H. 1979, Rev.Mod.Phys., 51, 715.Google Scholar
Edelson, R.A., and Krolik, J.H., 1988 (preprint) Google Scholar
Elitzur, M., and Ferland, G.J., 1985, Ap.J. Google Scholar
Fabian, A.C., Guilbert, P.W., Arnud, K., Shafer, R.A., Tennant, A.F. and Ward, M.J., 1986, MNRAS, 218, 457.Google Scholar
Ferland, G.J., and Rees, M., 1988 Ap.J. (in press) Google Scholar
Ferland, G.J. and Shields, G.A., 1985 in Astrophysics of Active Galaxies and QSOs (Miller, J. ed) p.157.Google Scholar
Gaskel, C.M., 1983, Liege, Ast.Coll., 24, 473.Google Scholar
Gaskell, C.M., and Peterson, B.M., 1987, Ap.J. Supp., 65, 1.Google Scholar
Gaskell, C.M., and Sparke, , 1986, Ap.J., 305, 175.Google Scholar
Gondhalekar, P.M., 1988, (submitted to MNRAS) Google Scholar
Hubbard, E.M., nd Puetter, R.C., 1985, Ap.J., 290, 394.Google Scholar
Joly, M., Collin-Souffrin, S., Masnau, J.L., and Nottale, L., 1985, Astr.Ap. 152, 282.Google Scholar
Joly, M., 1987, in Emission Lines in Active Galactic Nuclei, (Gondhalekar, P. ed. p160)Google Scholar
Joly, M., 1987, Astr.Ap. 184, 33.Google Scholar
Kazanas, D., 1988 (preprint) Google Scholar
Kinney, A.L., Huggins, P.J., Glassgold, A.E., and Bregman, J.N., 1987, Ap.J., 314, 145.Google Scholar
Krolik, J.H., 1988, Ap.J. 325, 182.Google Scholar
Krolik, J., McKee, C.M., and Tarter, C.B., 1981, Ap.J. 249, 422.Google Scholar
Kwan, J., and Krolik, J.H. 1981, Ap.J., 250, 478.Google Scholar
Laor, A., and Netzer, H., 1988, (MNRAS, submitted) Google Scholar
Lawrence, A. et al, 1988, MNRAS (submitted) Google Scholar
Madau, P., 1988, Ap.J., 327, 116.Google Scholar
Maoz, D., and Netzer, H., 1988, (MNRAS, accepted) Google Scholar
MacAlpine, G.M., 1972, Ap.J., 175, 11.CrossRefGoogle Scholar
MacAlpine, G.M., 1985 in Astrophysics of Active Galaxies and QSOs, (Miller, J. ed). p.259.Google Scholar
MacAlpine, G.M. Davidson, K., Gull, T.R., and Wu, C.C., 1985, Ap.J., 294, 147.Google Scholar
Malkan, M.A., and Sargent, W.C.W., 1982, Ap.J. 254, 122.CrossRefGoogle Scholar
Mathews, W.G., and Ferland, G.J., 1987, Ap.J. Google Scholar
Mathews, W.G., and Capriotti, E.R., 1985, in strophysics of Active Galaxies and QSOs (Miller, J. ed) p.185.Google Scholar
Mushotzky, R.F., and Ferland, G.J., 1984, Ap.J. 278, 558.Google Scholar
Netzer, H. 1985a, Ap.J. 289, 451.Google Scholar
Netzer, H., 1985b, MNRAS, 216, 63.Google Scholar
Netzer, H. 1987, MNRAS., 225, 55.Google Scholar
O'Brien, P.T., 1987, in Emission Lines in Active Galactic Nuclei (Gondhalekar, P. ed), p35.Google Scholar
Penston, M.V., 1988, MNRAS, 233, 601.Google Scholar
Perez, E., Penston, M.V., Tadhunter, C., Mediaville, E., and Moles, M., 1988, MNRAS, 230, 353.Google Scholar
Peterson, B.M., 1988, Pub.Astr.Soc.Pac., 100, 18.Google Scholar
Peterson, B.M., Meyers, K.A., Capriotti, E.R., Foltz, C.B., Wilkes, B.J., and Miller, H.R., 1985, Ap.J., 2 Google Scholar
Rees, M., 1987, MNRAS, 228, 47p.Google Scholar
Rees, M., Netzer, H., and Ferland, G.J., (in preparation).Google Scholar
Scoville, N., and Collin, A.N., 1988 (preprint) Google Scholar
Shakura, N.I., and Sunyaev, R.A., 1973, Astr.Ap., 24, 337.Google Scholar
Shields, G.A., 1978, Nature, 272, 706.Google Scholar
Smith, P.S., Elston, R., Berrinan, G., and Allen, R.G., 1988, Ap.J. Lett., 326, L39.Google Scholar
Wampler, E.J., Gaskell, C.M., Burk, W.L., and Baldwin, J.A., 1984, Ap.J., 276, 403.Google Scholar
Wandel, A., and Yahil, A., Ap.J., 295, L1.Google Scholar
Ward, M.J., Done, C., Fabian, A.C., Tennant, A.F., and Shafer, R.A., 1987, Ap.J.,Google Scholar
Wilkes, B.J., Elvis, M., and McHardy, I., 1987, Ap.J. Lett. 321, L23.Google Scholar
Wills, B.J., 1985 (Proc. of IAU symp. no. 110, p279) Google Scholar
Wills, B.J., Netzer, H., and Wills, D. 1985, Ap.J., 288, 94.Google Scholar
Wills, B.J., and Browne, I.W., 1986, Ap.J., 302, 56.Google Scholar
Zheng, W., Burbidge, E.M., Smith, H.E., Cohe, R.D., and Bradley, S.E., 1987, Ap.J. 322, 164.Google Scholar