1990 Fiscal Year Final Research Report Summary
Studies of Accretion Flow onto a Neutron Star
| Project/Area Number |
01460011
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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 | Rikkyo University |
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Principal Investigator |
HOSHI Reiun Rikkyo University, Department of Physics, Professor, 理学部, 教授 (70062601)
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| Co-Investigator(Kenkyū-buntansha) |
INOUE Hajime Institute of Space and Astronautical Science, Associate Professor, 助教授 (40092142)
SHIBAZAKI Noriaki Rikkyo University, Department of Physics, Associate Professor, 理学部, 助教授 (50206124)
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| Project Period (FY) |
1989 – 1990
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| Keywords | QPO / X-Ray Star / Mass Accretion |
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| Research Abstract |
We have studied the energy spectral properties and quasi-periodic oscillations (QPO) of X-ray intensities especially from the low mass binary X-ray stars. We have proceeded an investigation performing an intimate interplay between theory and observation. We have obtained the following important results from Ginga observations :
(1) a discovery of noncorrelated variation in power between the horizontal branch QPO and the low frequency noise
(2) detectins of QPOs from X-ray pulsars Cen X-3 and 4U 1626-67
(3) a discovery of a shallow and broad absorption feature in the 7-20 keV range of the energy spectrum of 4U 1608-522
(4) a detection of 2-6 Hz QPOs from X-ray transient GS 1124-68
The main results of theoretical studies are summarized as follows :
(1) Conducting a shot noise simulation, we found that the plasma clump-magnetic field interaction used in the beat frequency model cannot explain the observed fact (1).
(2) QPO of X-ray pulsars may be interpreted as a beat frequency intensity modulation.
(3) A shallow broad absorption structure in the energy spectra may be due to the reflection of a part of X-rays from the neutron star surface in the outer part of the disk.
(4) The low frequency QPOs as observed from GS 1124-68 may be due to the waves excited in the accretion disk.
Our studies here provided us with an important basis to understand the accretion flow onto a neutron star. More studies should be done to elucidate the detailed properties of the accretion flow.
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