| Project/Area Number |
16340057
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | Kyoto University |
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Principal Investigator |
MINESHIGE Shin Kyoto University, Yukawa Inst.for Theoretical Phys., Prof., 基礎物理学研究所, 教授 (70229780)
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| Co-Investigator(Kenkyū-buntansha) |
NOGAMI Daisaku Kyoto University, Graduate School of Science, Assist.Prof., 大学院理学研究科, 助手 (20332728)
OKITA Kiichi Nat.Astron.Obs., Opt.Infra.Obs.Section, Assoc.Prof, 光学赤外線天文学・観測システム系, 助教授 (60204096)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥16,500,000 (Direct Cost: ¥16,500,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2004: ¥12,400,000 (Direct Cost: ¥12,400,000)
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| Keywords | black hole / particle acceleration / non-thermal particles / high-speed photometry / CCD camera / magnetic fields / synchrotron emission / self-organized criticality / 高速CCD / 放射場 / 時間変動 / 逆コンプトン散乱 / 磁気リコネクション / 観測機器開発 / X線連星系 / 磁気ダイナモ |
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| Research Abstract |
Black hole objects show violent activities in their radiation. The aim of this project is to observe short-term optical variability with the time resolution of less than 0.1 sec so as to clarify its underlying physical mechanism. Through three-year research, we have obtained the following results :
1)Construction of the high-speed photometry system and observations
By using the CCD camera (CCD87 chip made by e2v co.), which enables us to take 33 pictures/sec, we have constructed a high-speed photometry system. This system was attached to the 1.5m (diameter) "Kanata" telescope at the Higashi-Hiroshima Observatory and was used to observe a prototype black hole, Cygnus X-1. The observations was successful and we found a new type of flares with duration less than a sec.
2)Short-term variations from simulated magnetohydrodynamical (MHD) flow
We have performed global, MHD simulations starting with a torus threaded with poloidal magnetic fields. Then, the toroidal magnetic fields are created and accumulated around the center, producing an inflated magnetic structure (magnetic tower), which drives strong mass and magnetic field outflows (jets). We also calculated radiation spectra based on the simulation data, finding short-term variability in optical lights.
3)A simple model of black hole variability
We proposed a new cellular-automaton model for variability of black-hole objects. The cellular-automaton rule which describes the procedure of model calculations is based on the induction equation and consists with two processes: input of fluctuation in the magnetic field and dissipation of magnetic energy in the form of magnetic reconnection. This model can well reproduce the basic observational features of the black-hole variability, such as aperiodic fluctuation light curves, 1/f-type fluctuation power spectra, and lognormal flux distribution. The success strongly indicates magnetic fields being the origin of producing black-hole variability.
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