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	Scale-free thin discs with an isopedic magnetic field
	Wu, Yue ; Lou, Yu-Qing
	2010-05-06 ; 2010-05-06
关键词	MHD waves ISM : general galaxies : kinematics and dynamics galaxies : spiral galaxies : structure SINGULAR ISOTHERMAL DISCS SLOW DENSITY WAVES POWER-LAW DISCS SPIRAL STRUCTURE COMPOSITE SYSTEM ACCRETION DISKS PERTURBATION CONFIGURATIONS NUMERICAL EXPERIMENTS ENVELOPE EXPANSION STABILITY ANALYSIS Astronomy & Astrophysics
中文摘要	Global stationary configurations of both aligned and logarithmic spiral magnetohydrodynamic (MHD) perturbations are constructed analytically within an axisymmetric background of razor-thin scale-free gas disc, which is embedded in an axisymmetric gravitational potential of a dark matter halo and involves an isopedic magnetic field almost vertically threaded through the disc plane. The scale-free index beta of the disc rotation speed v(theta) proportional to R-beta falls in the range of (-1/2, 1/2) where R is the cylindrical radius. With the holding-back of a deep background dark matter halo potential, the isopedic magnetic field may be strong enough to allow for the magnetic tension force overtaking the disc self-gravity, which can significantly influence global stationary MHD perturbation configurations and stability properties of the scale-free disc system. Only for stationary logarithmic spiral MHD perturbations with a perturbation scale-free index beta(1) = 1/4 or for aligned stationary MHD perturbations, can the MHD disc maintain a constant radial flux of angular momentum. The variable radial flux of angular momentum in the radial direction corresponds to a complex dispersion relation. The marginal instabilities for axisymmetric MHD disturbances are also examined for a special case as an example. When the magnetic tension force overtakes the disc self-gravity, the scale-free disc can be completely stable against axisymmetric MHD disturbances of all wavelengths. We predict the possible existence of an isopedically magnetized gas disc system in rotation primarily confined by a massive dark matter halo potential.
语种	英语 ; 英语
出版者	BLACKWELL PUBLISHING ; OXFORD ; 9600 GARSINGTON RD, OXFORD OX4 2DQ, OXON, ENGLAND
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/14536]
专题	清华大学
推荐引用方式 GB/T 7714	Wu, Yue,Lou, Yu-Qing. Scale-free thin discs with an isopedic magnetic field[J],2010, 2010.
APA	Wu, Yue,&Lou, Yu-Qing.(2010).Scale-free thin discs with an isopedic magnetic field..
MLA	Wu, Yue,et al."Scale-free thin discs with an isopedic magnetic field".(2010).

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