Numerical Simulations of Accretion Flows onto a Compact Object in a Close Binary System

封闭二元系统中紧凑物体吸积流的数值模拟

基本信息

批准号：
61540183
负责人：
MATSUDA Takuya
金额：
$ 1.34万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61540183/
关键词：
Accretion X-Ray Stars Spinup Spindown Galaxy Spiral Arm Numerical Simulation アクリーション円盤 X線パルサー近接連星系

项目摘要

Numerical simulations on an accretion flow and a related problem were performed. There are two types of accretion flow in a close binary system depending on the mangitude of the angular momentum of the accreting gas: a Roche lobe overflow and a wind-fed accretion. In the former case we have pointed out the existence of spiral shock waves on an accretion disc. In the present work our numerical results show good agreement with the anlytic solution obtained by Spruit. According to his theory there is a close relation between the pitch angle of the spiral shocks and the specific heat ratio. The smaller the specific heat ratio, the smaller the pitch angle. We have shown that accretion can occur even without a viscosity in some cases.Relating to the problem of the accretion, we have investigated the problem of spiral arm formation in a disc galaxy. In our view, the cause of spiral arms are a deviatin of gravitational force from the exact axisymmetry. In the accretin disc very similar phenomenon occurs due to the tidal force.We have also investigated the wind-fed accretion and the angular momentum accretion on to a compact object in a close binary system. We found that the flow is unsteady and the sign of the angular momentum of the accreting gas changes randomly with time. Although this is an unexpected result, Taam & Fryxcell in USA recently confirmed our results by their extensive numerical simulations. We have very new picture on the spin-up/down phenomena of a compact object. Our results can explain observations well.

进行了积聚流和相关问题的数值模拟。近距离二进制系统中有两种类型的积聚流，具体取决于积聚气体的角动量的操纵：Roche Lobe Overflow和风馈积聚。在前一种情况下，我们指出了积聚盘上存在螺旋冲击波。在目前的工作中，我们的数值结果与Spruit获得的闭环解决方案表示很好。根据他的理论，螺旋冲击的螺距角度与特定的热比之间存在密切的关系。比率越小，螺距角度越小。我们已经表明，即使在某些情况下也没有粘度，也可以发生增生。与积聚的问题相关，我们研究了圆盘银河系中螺旋形成的问题。在我们看来，螺旋臂的原因是重力与精确轴对称性的偏离。在增生蛋白盘中，由于潮汐力而发生非常相似的现象。我们还研究了在近距离二进制系统中的强力积聚和角动量积聚到紧凑的物体上。我们发现流动不稳定，积聚气体的角动量随着时间而随机变化。尽管这是一个出乎意料的结果，但美国的Taam＆Fryxcell最近通过广泛的数值模拟证实了我们的结果。我们在紧凑型物体的旋转/下降现象上有非常新的图片。我们的结果可以很好地解释观察结果。