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arXiv 0905.1593astro-ph.GAastro-ph.IM
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暗物质主导星系中的星团演化

Star Cluster Evolution in Dark Matter Dominated Galaxies

A. K. Praagman, J. R. Hurley, C. Power

摘要:

我们研究了暗物质晕的外部潮汐场对星团动力学演化的影响,采用直接N体模拟方法,假设暗物质晕是由Navarro,Frenk & White质量分布描述的,该质量分布具有内部密度尖点.我们评估如何改变质量和浓度的晕影响的速度在星团失去质量,我们发现,增加晕质量和浓度驱动增强质量损失率和原则上较短的集群中断时间尺度。此外,我们研究中断的时间尺度在一个星系的三个组件模型(凸起,磁盘和暗物质晕),并找到良好的协议与结果的基础上的经验模型的银河系的潜力,如果我们假设晕质量的~ 1 E12太阳质量。一般来说,暗物质晕对星系质量的贡献很大,在模拟星团演化时不应忽略。我们扩展我们的研究结果,讨论这可能有一个潜在的深远影响的破坏时间尺度的球状星团,这表明我们可能低估了速度,原始球状星团被打乱。

英文摘要:

We investigate the influence of the external tidal field of a dark matter halo on the dynamical evolution of star clusters using direct N-body simulations, where we assume that the halo is described by a Navarro, Frenk & White mass profile which has an inner density cusp. We assess how varying the mass and concentration of the halo affects the rate at which the star cluster loses mass and we find that increasing halo mass and concentration drives enhanced mass loss rates and in principle shorter cluster disruption timescales. In addition, we examine disruption timescales in a three-component model of a galaxy (bulge, disk and dark matter halo) and find good agreement with results based on an empirical model of the Galactic potential if we assume a halo mass of ~1e12 solar masses. In general, dark matter halos are expected to contribute significantly to the masses of galaxies and should not be ignored when modelling the evolution of star clusters. We extend our results to discuss how this can have a potentially profound effect on the disruption timescales of globular clusters, suggesting that we may underestimate the rate at which primordial globular clusters are disrupted.

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