Relaxation in stellar systems, and the shape and rotation of the inner dark halo

被引:35
作者
Tremaine, S [1 ]
Ostriker, JP [1 ]
机构
[1] Princeton Univ Observ, Princeton, NJ 08544 USA
基金
美国国家科学基金会;
关键词
galaxies : evolution; galaxies : formation; galaxies : haloes; galaxies : kinematics and dynamics;
D O I
10.1046/j.1365-8711.1999.02558.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Why do galactic bars rotate with high pattern speeds, when dynamical friction should rapidly couple the bar to the massive, slowly rotating dark halo? This long-standing paradox may be resolved by considering the dynamical interactions between the galactic disc and structures in the dark halo. Dynamical friction between small-scale halo structure and the disc spins up and flattens the inner halo, thereby quenching the dynamical friction exerted by the halo on the bar; at the same time the halo heats and thickens the inner disc, perhaps forming a rapidly rotating bulge. Two possible candidates for the required halo structures are massive black holes and tidal streamers from disrupted precursor haloes. More generally, gravitational scattering from phase-wrapped inhomogeneities represents a novel relaxation process in stellar systems, intermediate between violent relaxation and two-body relaxation, which can isotropize the distribution function at radii where two-body relaxation is not effective.
引用
收藏
页码:662 / 668
页数:7
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