Studies of Accretion Flow onto a Neutron Star

我们研究了x射线强度的能谱特性和准周期振荡（QPO），特别是来自低质量双星的x射线。我们进行了一项调查，在理论和观察之间进行了密切的相互作用。我们得到以下重要Ginga观察结果:(1)发现noncorrelated变异水平分支QPO之间在权力和低频噪声(2)detectins QPO从x射线脉冲星岑- 3和4 u 1626 - 67(3)发现了一个浅和广泛的吸收特性7-20 keV范围的能量谱的4 u 1608 - 522(4)从x射线检测2 - 6赫兹QPO瞬态GS 1124 - 68理论研究的主要成果总结如下:(1)通过散粒噪声模拟，我们发现在拍频模型中使用的等离子体团块-磁场相互作用不能解释观测到的事实(1)。(2)x射线脉冲星的QPO可以解释为拍频强度调制。(3)能谱上较浅的宽吸收结构可能是由于中子星表面部分x射线在盘外部分的反射所致。(4) GS 1124-68观测到的低频qpo可能是由吸积盘中激发的波引起的。我们在这里的研究为我们了解中子星的吸积流提供了重要的基础。需要做更多的研究来阐明吸积流的详细性质。

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 1124-68The 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.