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	Global non-axisymmetric perturbation configurations in a composite disc system with an isopedic magnetic field: relation between dark matter halo and magnetic field
	Xiang-Gruess, Meng ; Lou, Yu-Qing ; Duschl, Wolfgang J.
	2010-10-12 ; 2010-10-12
关键词	MHD waves galaxies: haloes galaxies: ISM galaxies: kinematics and dynamics galaxies: magnetic fields SINGULAR ISOTHERMAL DISCS SCALE-FREE DISCS GALACTIC GAS DISKS SPIRAL GALAXIES NEUTRAL-HYDROGEN ROTATION CURVES DENSITY WAVES ACCRETION DISKS MODAL APPROACH STABILITY Astronomy & Astrophysics
中文摘要	We study global non-axisymmetric stationary perturbations of aligned and unaligned logarithmic spiral configurations in an axisymmetric composite differentially rotating disc system of scale-free stellar and isopedically magnetized gas discs coupled by gravity. The infinitely thin gas disc is threaded across by a vertical magnetic field B-z with a constant dimensionless isopedic ratio of surface gas mass density Sigma((g)) to B-z with G being the gravitational constant. Our exploration focuses on the relation between the isopedic ratio lambda and the dark matter amount represented by a gravitational potential ratio in order to sustain stationary perturbation configurations, where is the gravitational potential of a presumed axisymmetric halo of dark matter and is the gravitational potential of the composite disc matter. For typical disc galaxies, we explore relevant parameter ranges numerically. High and low lambda values correspond to relatively weak and strong magnetic fields given the same gas surface mass density, respectively. The main goal of our model analysis is to reveal the relation between isopedic magnetic fields and dark matter halo in spiral galaxies with globally stationary perturbation configurations. Our results show that for stationary perturbation configurations, fairly strong yet realistic magnetic fields require a considerably larger amount of dark matter in aligned and unaligned cases than weak or moderate magnetic field strengths. We discuss astrophysical and cosmological implications of our findings. For examples, patterns and pattern speeds of galaxies may change during the course of galactic evolution. Multiple-armed galaxies may be more numerous in the early Universe. Flocculent galaxies may represent the transitional phase of pattern variations in galaxies.
语种	英语 ; 英语
出版者	WILEY-BLACKWELL PUBLISHING, INC ; MALDEN ; COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/81600]
专题	清华大学
推荐引用方式 GB/T 7714	Xiang-Gruess, Meng,Lou, Yu-Qing,Duschl, Wolfgang J.. Global non-axisymmetric perturbation configurations in a composite disc system with an isopedic magnetic field: relation between dark matter halo and magnetic field[J],2010, 2010.
APA	Xiang-Gruess, Meng,Lou, Yu-Qing,&Duschl, Wolfgang J..(2010).Global non-axisymmetric perturbation configurations in a composite disc system with an isopedic magnetic field: relation between dark matter halo and magnetic field..
MLA	Xiang-Gruess, Meng,et al."Global non-axisymmetric perturbation configurations in a composite disc system with an isopedic magnetic field: relation between dark matter halo and magnetic field".(2010).

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