| Time Scales and Tidal Effects in Minor Mergers |
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| 作者姓名： | Yu Lu and Jian-Yan Wei
National Astronomical Observatories Chinese Academy of Sciences Beijing luyu |
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| 作者单位： | Yu Lu and Jian-Yan Wei
National Astronomical Observatories，Chinese Academy of Sciences，Beijing 100012; luyu |
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| 基金项目： | Supported by the National Natural Science Foundation of China |
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| 摘 要： | We use controlled N-body simulation to investigate the dynamical processes (dynamical friction, tidal truncation, etc.) involved in the merging of small satellites into bigger halos. We confirm the validity of some analytic formulae proposed earlier based on simple arguments. For rigid satellites represented by softened point masses, the merging time scale depends on both the orbital shape and concentration of the satellite. The dependence on orbital ellipticity is roughly a power law, as suggested by Lacey & Cole, and the dependence on satellite concentration is similar to that proposed by White. When merging satellites are represented by non-rigid objects, Tidal effects must be considered. We found that material beyond the tidal radius are stripped off. The decrease in the satellite mass might mean an increase in the merging time scale, but in fact, the merging time is decreased, because the stripped-off material carries away a proportionately larger amount of of orbital energy and angular momentum.
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| 关 键 词： | 宇宙学 暗物质 动力学 运动学 恒星物理学 结构 交互作用 数值分析 涨落效应 时间尺度效应 |
Time Scales and Tidal Effects in Minor Mergers |
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| Yu Lu and Jian-Yan Wei
National Astronomical Observatories,Chinese Academy of Sciences,Beijing , luyu.Time Scales and Tidal Effects in Minor Mergers[J].Chinese Journal of Astronomy and Astrophysics,2003,3(5):395-409. |
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| Authors: | Yu Lu Jian-Yan Wei |
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| Abstract: | We use controlled N-body simulation to investigate the dynamical processes (dynamical friction, tidal truncation, etc.) involved in the merging of small satellites into bigger halos. We confirm the validity of some analytic formulae proposed earlier based on simple arguments. For rigid satellites represented by softened point masses, the merging time scale depends on both the orbital shape and concentration of the satellite. The dependence on orbital ellipticity is roughly a power law, as suggested by Lacey & Cole, and the dependence on satellite concentration is similar to that proposed by White. When merging satellites are represented by non-rigid objects, Tidal effects must be considered. We found that material beyond the tidal radius are stripped off. The decrease in the satellite mass might mean an increase in the merging time scale, but in fact, the merging time is decreased, because the stripped-off material carries away a proportionately larger amount of of orbital energy and angular momentum. |
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| Keywords: | cosmology: dark matter - galaxies: kinematics and dynamics - galaxies: structure - galaxies: interactions - numerical methods |
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