Infrared Emission and H20 Masers around Massive Black Holes in Galactic Nuclei
Many galaxies exhibit evidence for nonstellar sources of energy in their centers . The most extreme examples of these active galactic nuclei (AGN)—quasars— reach extraordinary luminosities, exceeding 1047 erg s–1 (about 1013 times the luminosity of the Sun). Time-variability arguments indicate that this energy must arise in very compact regions (≲ 1016 cm). The generally accepted mechanism for powering AGN is accretion of gas onto a massive black hole: a central black hole of mass 106 — 109 solar masses (M⊙) is surrounded by an orbiting accretion disk which may extend ~ 0.1 — 1 pc (1 pc is about 3 light-years) from the black hole. Gaseous material spirals through this disk onto the black hole at rates M ~ 10–4—1 M⊙ yr–1, and a fraction 蜒 ~ 0.1 of the gravitational rest-mass energy is converted to radiation .
KeywordsBlack Hole Accretion Disk Active Galactic Nucleus Column Density Massive Black Hole
Unable to display preview. Download preview PDF.
- R. D. Blandford, in Courvoisier and Mayor, op. cit., p. 161Google Scholar
- I. N. Evans, Z. Tsvetanov, G. A. Kriss, H. C. Ford, S. Caganoff, and A. P. Koratkar, ApJ 417, 82 (1993).Google Scholar
- M. J. Claussen, G. M. Heiligman, and K.-Y. Lo, Nature 278, 34 (1984).Google Scholar
- P. R. Maloney, D. J. Hollenbach, and A.G.G.M. Tielens, ApJ, submitted (1995).Google Scholar
- J. H. Black, in Interstellar Processes, ed. D. J. Hollenbach and H. A. Thronson (Dordrecht, Reidel, 1987 ), p. 731.Google Scholar
- J. Frank, A. King, and D. Raine, Accretion Power in Astrophysics ( Cambridge, Cambridge University Press, 1992 ) p. 62.Google Scholar
- D. A. Neufeld and P.R. Maloney, ApJ(Letters), in press (1995).Google Scholar