DYNAMICAL FRICTION IN CUSPY GALAXIES
DYNAMICAL FRICTION IN CUSPY GALAXIES
复制标题
尖尖星系中的动态摩擦
DOI：
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发表时间：
2011
期刊：
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通讯作者：
R. Capuzzo
中科院分区：
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作者：
M. Arca;R. Capuzzo
本文讨论了质量密度为尖点分布的椭圆星系中质量物体运动的动力学摩擦衰变问题。我们给出了通过自洽、直接求和、N体模拟以及对这种尖锐的星系中心区有效的动力摩擦的一种新的半解析处理所获得的结果。这些结果的比较表明，所提出的半解析近似是在陡峭的银河系中心区唯一可靠的近似，在那里标准的Chandrasekhar局部近似不成立，并且还给出了衰变时间的估计，相对于N体模拟给出的估计准确度为1%。研究发现，弯曲星系的动力摩擦效率明显高于核心星系，尤其是在径向拉长的卫星轨道上。作为另一个相关的结果，我们发现动力学摩擦衰减时间与卫星质量的−0.67次方的比例比标准采用的M−1关系要浅。
In this paper, we treat the problem of the dynamical friction decay of a massive object moving in an elliptical galaxy with a cuspidal inner distribution of the mass density. We present results obtained by both self-consistent, direct summation, N-body simulations, as well as by a new semi-analytical treatment of dynamical friction valid in such cuspy central regions of galaxies. A comparison of these results indicates that the proposed semi-analytical approximation is the only reliable one in cuspy galactic central regions, where the standard Chandrasekhar's local approximation fails and also gives estimates of decay times that are correct at 1% with respect to those given by N-body simulations. The efficiency of dynamical friction in cuspy galaxies is found definitively higher than in core galaxies, especially on more radially elongated satellite orbits. As another relevant result, we find a proportionality of the dynamical friction decay time to the −0.67 power of the satellite mass, M, shallower than the standardly adopted M−1 dependence.