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The Origin of Continuum Emission in Active Galactic Nuclei

Published online by Cambridge University Press:  19 July 2016

Joel N. Bregman
Joel N. Bregman*
Affiliation:
Department of Astronomy, University of Michigan

Abstract

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The general understanding of the continuum emission from AGN has changed from the picture where nonthermal processes were responsible for all of the emission. The current body of observation indicates that there are two types of objects, one being the blazar class (or blazar component), where nearly all of the emission is nonthermal, due primarily to synchrotron and inverse Compton emission. Variability studies indicate that the emitting region decreases with size from the radio through the X-ray region, where the size of the X-ray region is of order a light hour. More than two dozen of these radio-loud AGNs have been detected at GeV energies (one source at TeV energies), for which the radiation mechanism may be inverse Compton mechanism.

In the other class, the radio-quiet AGN (component), the emission is almost entirely thermal, with radiation from dust dominating the near infrared to submillimeter region. The optical to soft X-ray emission is often ascribed to black body emission from an opaque accretion disk, but variability studies may not be consistent with expectations. Another attractive model has free-free emission being responsible for the optical to soft X-ray emission. The highest frequencies at which these AGN are detected is the MeV range, and these data should help to determine if this emission is produced in a scattering atmosphere, such as that around an accretion disk, or by another model involving an opaque pair plasma.

Type
Multi-wavelength Continuum Emission of AGN
Information
Symposium - International Astronomical Union , Volume 159: Multi-Wavelength Continuum Emission of AGN , 1994 , pp. 5 - 16
Copyright
Copyright © Kluwer 1994 

References

Antonucci, R.R.J., Kinney, A.L., and Ford, H.C. 1989, Ap. J. , 342, 64.Google Scholar
Barvainis, R. 1987, Ap. J. , 320, 537.Google Scholar
Barvainis, R. 1992, Ap. J. , 400, 502.CrossRefGoogle Scholar
Barvainis, R., and Antonucci, R. 1989, Ap. J. Sup. Ser. , 70, 173.Google Scholar
Barvainis, R. 1993, Ap. J. , 412, 513.Google Scholar
Beichman, C.A., Neugebauer, G., Soifer, B.T., Wootten, H.A., Roellig, T., and Harvey, P.M. 1981a, Nature , 293, 711.CrossRefGoogle Scholar
Beichman, C.A., Provdo, S.H., Neugebauer, G., Soifer, B.T., Matthews, K., and Wootten, H.A. 1981b, Ap. J. , 247, 780.Google Scholar
Bloom, S.D., and Marscher, A.P. 1993, in Proceedings of the Compton Observatory Symposium , ed. Gehrels, N. (New York: AIP), in press.Google Scholar
Bregman, J.N. 1990, Astr. Ap. Rev. , 2, 125.Google Scholar
Bregman, J.N., et al. 1981, Nature , 293, 714.CrossRefGoogle Scholar
Bregman, J.N., et al. 1990, Ap. J. , 352, 574.CrossRefGoogle Scholar
Bridle, A.H., and Perley, R.A. 1984, Ann. Rev. Astr. Ap. , 22, 319.Google Scholar
Browne, L.M.J., et al. 1989a, Ap. J. , 340, 129.Google Scholar
Browne, L.M.J., et al. 1989b, Ap. J. , 340, 162.Google Scholar
Carini, M.T., and Miller, H.R. 1992, Ap. J. , 385, 146.Google Scholar
Carini, M.T., and Miller, H.R., Noble, J.C., and Goodrich, B.D. 1992, Astr. J. , 104, 15.Google Scholar
Carleton, N.P., et al. 1987, Ap. J. , 318, 595.Google Scholar
Celotti, A., Fabian, A.C., and Rees, M.J. 1992, M.N.R.A.S. , 255, 419.Google Scholar
Celotti, A., Maraschi, L, and Treves, A. 1991, Ap. J. , 377, 403.Google Scholar
Chen, K., Halpern, J.P., and Filippenko, A.V. 1989, Ap. J. , 339, 742.Google Scholar
Chini, R., Steppe, H., Kreysa, E., Krichbaum, T., Quirrenbach, A., Schalinski, C., and Witzel, A. 1988, Astr. Ap. , 192, L1.Google Scholar
Chini, R., Kreysa, E., and Biermann, P.L. 1989, Astr. Ap. , 219, 87.Google Scholar
Clavel, J., Wamsteker, W., and Glass, I.S. 1989, Ap. J. , 337, 236.Google Scholar
Clement, R., Sembay, S., Hanson, C.G., and Coe, M.J. 1988, M.N.R.A.S. , 230, 117.Google Scholar
Couroisier, T.J.-L, and Clavel, J. 1991, Astr. Ap. , 248, 389.Google Scholar
Cutri, R.M., Wisniewski, W.Z., Rieke, G.H., and Lebofsky, M.J. 1985, Ap. J. , 296, 423.CrossRefGoogle Scholar
Done, C., and Fabian, A.C. 1989, M.N.R.A.S. , 240, 81.CrossRefGoogle Scholar
Doxsey, R. et al. 1983, Ap. J. , 264, L43.Google Scholar
Draine, B.T. 1990, in The Interstellar Medium in Galaxies , ed. Thronson, H.A., and Shull, J.M. (Kluwer: Dordrecht), p. 483.Google Scholar
Edelson, R.A., and Malkan, M.A. 1986, Ap. J. , 308, 59.Google Scholar
Edelson, R.A., and Malkan, M.A. 1987, Ap. J. , 323, 516.Google Scholar
Edelson, R.A., et al. 1994, Ap. J. , in press.Google Scholar
Feigelson, E.D., et al. 1986, Ap. J. , 302, 337.Google Scholar
Ferland, G.J., Korista, K.T., and Peterson, B.M. 1990, Ap. J. , 363, L21.Google Scholar
Gabuzda, D.C., Wardle, J.F.C., and Roberts, D.H. 1989, Ap. J. , 336, L59.Google Scholar
Ghisellini, G., Maraschi, L., Tanzi, E., Treves, A. 1986, Ap. J. , 310, 317.Google Scholar
Ghisellini, G., Padovani, P., Celotti, A., and Maraschi, L. 1993, Ap. J. , 407, 65.Google Scholar
Giommi, P., et al. 1986, Ap. J. , 303, 596.Google Scholar
Glass, I.S., 1992, M.N.R.A.S. , 256, 23P.Google Scholar
Haardt, F., and Maraschi, L. 1991, Ap. J. , 380, L51.Google Scholar
Halpern, J.P. 1990, Ap. J. , 365, L51.Google Scholar
Hartman, R.C. et al. 1993, Ap. J. , 407, L41.CrossRefGoogle Scholar
Hufnagel, B.R., and Bregman, J.N. 1992, Ap. J. , 386, 473.Google Scholar
Hughes, D.H., Robson, E.I., Dunlop, J.S., and Gear, W.K. 1993, M.N.R.A.S. , 263, 607.CrossRefGoogle Scholar
Hughes, P.A., Aller, H.D., Aller, M.F. 1989a, Ap. J. , 341, 54.Google Scholar
Hughes, P.A., Aller, H.D., Aller, M.F. 1989b, Ap. J. , 341, 68.Google Scholar
Jones, T.W., O'Dell, S.L., and Stein, W.A. 1974, Ap. J. , 188, 353.Google Scholar
Kawai, N. et al. 1991, Ap. J. , 382, 508.Google Scholar
Kniffen, et al. 1993, Ap. J. , 411, 133.Google Scholar
Kolman, et al. 1993, Ap. J. , 402, 514.Google Scholar
Kotilainen, J.K., Ward, M.J., Boisson, C., DePoy, D.L., and Smith, M.G. 1992, M.N.R.A.S. , 256, 149.Google Scholar
Landau, R., et al. 1986, Ap. J. , 308, 78.Google Scholar
Laor, A., Netzer, H., and Piran, T. 1990, M.N.R.A.S. , 242, 560.Google Scholar
Malkan, M. 1989, in Theory of Accretion Disks , ed. Meyer, F., Duschl, W., Frank, J., and Meyer-Hofmeister, E. (Kluwer: Dordrecht), p. 19.Google Scholar
Malkan, M. 1991, in Structure and Emission Peoperties of Accretion Disks , ed. Bertout, C., Collin, S., Lasota, J.-P., Van, J. Tran Thanh, (Gif sur Yvette: Ed. Frontiers), p. 165.Google Scholar
Malkan, M.A., and Sargent, W.L.W. 1982, Ap. J. , 254, 22.Google Scholar
Maraschi, L., Ghisellini, G., Tanzi, E., Treves, A. 1986, Ap. J. , 310, 325.Google Scholar
Maraschi, L., and Molendi, S. 1991, Ap. J. , 368, 138.Google Scholar
Marscher, A.P., and Bloom, S.D. 1992, in Compton Observatory Science Workshop , p. 346.Google Scholar
Marscher, A.P., Gear, W.K., and Travis, J.P. 1992, in Variability of Blazars , ed. Valtaoja, E. and Valtonen, M.J. (Cambridge: CUP), p. 85.Google Scholar
Masnou, J.L., Wilkes, B.J., Elvis, M., McDowell, J.C., and Arnaud, K.A. 1992, Astr. Ap. , 253, 35.Google Scholar
Molendi, S., Maraschi, L., and Stella, L. 1992, M.N.R.A.S. , 255, 27.Google Scholar
Moore, R.L., and Stockman, H.S. 1981, Ap. J. , 243, 60.Google Scholar
Moore, R.L., and Stockman, H.S. 1984, Ap. J. , 279, 465.Google Scholar
Mushotzky, R.F., Done, C., and Pounds, K.A. 1993, Ann. Rev. Astr. Ap. , 31, 717.Google Scholar
Netzer, H. 1991, in Structure and Emission Properties of Accretion Disks , IAU Colloquium No. 129, p. 177.Google Scholar
Owen, F.N., Helfand, D.J., and Spangler, S.R. 1981, Ap. J. , 250, L55.Google Scholar
Padovani, P. 1992, Astr. Ap. , 256, 399.Google Scholar
Padovani, P., and Urry, C.M. 1992, Ap. J. , 387, 449.Google Scholar
Penston, M.V., Penston, M.J., Selmes, R.A., Becklin, E.E., and Neugebauer, G. 1974, M.N.R.A.S. , 169, 357.Google Scholar
Pounds, K.A., Nandra, K., and Stewart, G.C. 1992 in Ginga Memorial Symposium , ed. Makino, F. and Nagase, F. (ISAS: Tokyo), p. 45.Google Scholar
Punch, M. et al. 1992, Nature , 358, 477.Google Scholar
Rees, M.J., Silk, J.I., Werner, M.W., and Wickramsinghe, M.C. 1969, Nature , 223, 788.Google Scholar
Rees, M.J. 1984, Ann. Rev. Astr. Ap. , 22, 471.Google Scholar
Rieke, G.H., Lebofsky, M.J., and Kinman, T.D. 1979, Ap. J. , 232, L151.Google Scholar
Rieke, G.H., Lebofsky, M.J., Wisniewski, W.Z. 1982, Ap. J. , 263, 73.CrossRefGoogle Scholar
Sanders, D.B., Phinney, E.S., Neugebauer, G., Soifer, B.T., and Matthews, K. 1989, Ap. J. , 347, 29.Google Scholar
Shastri, , et al. 1993, Ap. J. , 410, 29.CrossRefGoogle Scholar
Sitko, M., Sitko, A.K., Siemiginowska, A., and Szczerba, R. 1993, Ap. J. , 409, 139.Google Scholar
Soifer, B.T., Houck, J.R., and Neugebauer, G. 1987, Ann. Rev. Astr. Ap. , 25, 187.Google Scholar
Sun, W.-H., and Malkan, M.A. 1989, Ap. J. , 346, 68.Google Scholar
Svensson, R. 1987, M.N.R.A.S. , 227, 403.Google Scholar
Tanaka, Y. 1992 in Ginga Memorial Symposium , ed. Makino, F. and Nagase, F. (ISAS: Tokyo), p. 19.Google Scholar
Telesco, C.M. 1988, Ann. Rev. Astr. Ap. , 26, 26.CrossRefGoogle Scholar
Turner, J. et al. 1993, Ap. J. , 407, 556.Google Scholar
Urry, C.M., et al. 1993, Ap. J. , 411, 614.CrossRefGoogle Scholar
Veilleux, S., and Zheng, W. 1991, Ap. J. , 377, 89.CrossRefGoogle Scholar
Walter, R., and Courvoisier, T.J.-L. 1992, Astr. Ap. , 266, 65.Google Scholar
Walter, R., and Fink, H.H. 1993, Astr. Ap. , 274, 105.Google Scholar
Zdziarski, A.A., Ghisellini, G., George, I.M., Svensson, R., Fabian, A.C., Done, C. 1990, Ap. J. , 363, L1.Google Scholar
Zdziarski, A.A., and Krolik, J.H. 1993, Ap. J. , 409, L33.CrossRefGoogle Scholar