2004 Fiscal Year Final Research Report Summary
Observational Study of the Massive Black Hole SgrA* and its Surrounding Field
| Project/Area Number |
15540242
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | National Astronomical Observatory Japan, NIH |
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Principal Investigator |
MIYOSHI Makoto National Astronomical Observatory Japan, NIH, Prime Researcher, 電波研究部, 主任研究員 (50270450)
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| Co-Investigator(Kenkyū-buntansha) |
DEGUCHI Shuji National Astronomical Observatory Japan, NIH, Assistant Professor, 野辺山宇宙電波観測所, 助教授 (20197825)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Galactic Center / Black Hole / mass distributions / SiO masers / delta VLBI / SgrA* |
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| Research Abstract |
1) We performed VLBA observations of several SiO masers around the massive black hole, SgrA* at the Galactic center. We detected proper motions of the three out of them with accuracy about 0.1mas/year. The results suggest that SgrA* may move relative to the surrounding stars. We also found the lower limit of the mass within 2 pc from the Galactic center is 2*10^6 solar mass.
2) Using the Nobeyama Millimeter wave Interferometer we monitored the flux density of SgrA* for short time flaring. There observed no flare of SgrA* within the observing session from Dec 2004 to May 2005.
3) We derived the mass (including dark matter) within 30 pc from the Galactic center by analyzing the statistics of line of sight velocities of SiO maser emissions from late type stars and by the use of integration of the Bolzmann equation along the line of sight. Unlike the distribution of OH masers, the one of the SiO masers follows the square of the distance from the Galactic center. Assuming that the central mass is the sum of the mass of central black hole and stellar system with the square law, we can make an equation of momentum of velocities from the line of sight integration of Bolzmann equation.
The mass of the Galactic center is M R=(2.69±1.30]+0.88[±0.07](R/pc)^{1.25)×10^6 solar mass.
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[Journal Article] VLBA observation of a radio intraday flare of Sgr A*2003
Author(s)
Miyoshi, M., Imai, H., Nakashima, J., Deguchi, S., Shen, Z.-Q.
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Journal Title
Astronomische Nachrichten, Supplementary Issue 324
Pages: 403
Description
「研究成果報告書概要(和文)」より
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