权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Study of Thermal Instability in Cooling Flow of Hot Intergalactic Gas in Clusters of Galaxies

星系团中星际热气体冷却流的热不稳定性研究

基本信息

批准号：
01540209
负责人：
HABE Asao
金额：
$ 0.19万
依托单位：
Hokkaido 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：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01540209/
关键词：
Formation and Evolution of Clusters of Galaxies Formation and Evolution of Galaxies Intergalactic Gas X-ray Astronomy Thermal Instability Numerical Hydrodynamics Magneto Hydrodynamics Creation and Development of Vorticities X線天文学銀河団の形成と

项目摘要

Thermal instability in cooling flows have been studied mainly by linear theory. By previous studies, it is pointed out that gravitational field of cluster of galaxies changes property of linear thermal instability. In order to clarify such effect on the mass deposition in cluster cooling flows, it is needed to study thermal instability in nonlinear stage in 2 or 3 dimension.In paper 1, we study non-linear perturbation in cluster cooling flow in a simple geometry, that is 2-dimension Cartesian coordinate, by using numerical hydrodynamics. We found that vortices are formed in the perturbation in cooling flows by the effect of gravitational field of cluster of galaxies and can suppress thermal instability of the perturbation. This phenomena is first found by us. We give the criterion that the perturbation cools before the vortex is formed.In the paper 2, we have adopted rather real situation for geometry of background cooling flow, that is spherical symmetric flow. We show that the formation of vortices and suppression of perturbations by these process actually occur in this case.In the paper 3, effect of magnetic field on thermal instability is studied by using numerical magneto-hydrodynamics. We have shown weak magnetic field suppress vortex formation and thermal instability is easy to occur by the effect of magnetic field. In this paper, we propose the mass depositon on process is regulated by the magnetic field in cluster of galaxies.

冷却流动的热不稳定性主要是用线性理论来研究的。前人的研究指出，星系团的引力场改变了星系团的线性热不稳定性。为了弄清这种对团簇冷却流动中质量沉积的影响，需要在二维或三维研究非线性阶段的热不稳定性。在论文1中，我们利用数值流体力学的方法，在一个简单的几何，即二维笛卡尔坐标下，研究了团簇冷却流动中的非线性摄动。我们发现，涡旋是在星系团引力场的作用下，在冷却流动的扰动中形成的，并能抑制扰动的热不稳定性。这一现象是我们首次发现的。给出了扰动在涡旋形成前冷却的判据，文2对背景冷却流的几何形状采用了较为真实的情况，即球对称流动。结果表明，在这种情况下，涡旋的形成和扰动的抑制确实发生了。在论文3中，我们用数值磁流体动力学方法研究了磁场对热不稳定性的影响。结果表明，弱磁场抑制了涡旋的形成，在磁场的作用下容易发生热不稳定性。在本文中，我们提出了星系团中的质量沉积过程是由磁场调节的。