1989 Fiscal Year Final Research Report Summary
Oscillations of Innermost Region of Relativistic Accretion Disks
| Project/Area Number |
63460010
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KATO Shoji Kyoto Univ. Astronomy Dept. Professor, 理学部, 教授 (80011534)
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| Co-Investigator(Kenkyū-buntansha) |
MATUSMOTO Ryoji Chiba Univ. College of Arts & Science Lecturer, 教養学部, 講師 (00209660)
INAGAKI Shogo Kyoto Univ. Astronomy Dept. Instructor, 理学部, 助手 (80115790)
ISHIZAWA Toshiaki Kyoto Univ. Astronomy Dept. Asoc. Prof., 理学部, 助教授 (10025398)
SAITO Mamoru Kyoto Univ. Astronomy Dept. Asoc. Prof., 理学部, 助教授 (90012856)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Relativistic Accretion / Oscillatory Phenomena / Instability / Quasi-Periodic Oscillations(QPO) |
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| Research Abstract |
Roughly speaking, we had two major results. The first is that (1)the innermost part of relativistic accretion disks is pulsationally unstable, when the so-called alpha-parameter of viscosity is larger than a critical value. The second is that(2) one-armed corrugation waves in the innermost part of relativistic accretion disks are low frequency oscillations whose frequencies are comparable with those of quasi-periodic oscillations (QPO's) observed in low mass X-ray binaries.
(1)The innermost part of relativistic accretion disks has the sonic point where the accretion flow becomes supersonic. We found analytically that the sonic point region is pulsationally unstable when viscosity is large. Subsequently this was confirmed by numerical simulations. Numerical simulations show further that the oscillations have long term variations. This modulation period was found to be comparable with that of QPO'S.
(2)As an oscillations mode whose frequency is as low as that of QPO's, we found one-armed corrugation waves. Corrugation waves are wavy oscillations of disks in the direction perpendicular to the disk plane. We found further that under some circumstances there corrugation waves can be trapped in the innermost part of relativistic accretion disks. This will be in favor of explaining QPO'S.
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[Publications] Kato, S., Honma, F., and Matsumoto, R.: "Viscous Pulsational Instability of Transonic Region of Isothermal Geometrically Thin Accretion Disks-I.Analytical Results," Monthly Not, Roy, Astr.Soc.Vol.231, 37-48, 1988.
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「研究成果報告書概要(欧文)」より
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[Publications] Matsumoto, R., Kato, S., and Honma, R.: "Pulsational Instability of Accretion Disks and QPO's," Physics of Neutron Stars and Black Holes, ed. by Y. Tanaka (Universal Academical Press, Tokyo), 155-158, 1988.
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[Publications] Kato, S., Okazaki, A.T., and Fukue, J.: "Trapped Oscillations of Disks in the Region around kappa_<max>, in Big Bang," Active Galactic Nuclei and Supernovae, ed. by S. Hayakawa and K. Sato (Universal Academical Press, Tokyo), 373-374, 1989.
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[Publications] Matsumoto, R., Kato, S., and Honma, F.: "Instability of Transonic Region of Accretion Disks and Time Variability of AGN's, in Big Bang," Active Galactic Nuclei and Supernovae, ed. by S.Hayakawa and K.Sato (Universal Academical Press, Tokyo), 353-354, 1989.
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[Publications] Matsumoto, R., Kato, S., and Honma, F.: "Non-linear Pulsation in the Transonic Region of Geometrically Thin Accretion Disks," The Theory of Accretion Disks, ed.F.Meyer, W.J.Duschl, J.Frank, and E.Meyer-Hofmeister(Kluwer Academic Publ., Derdrecht), 167-172, 1989.
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