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arXiv 1211.2802astro-ph.CO
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星系扰动对早型团矮星系球状星团系统的影响

The impact of galaxy harassment on the globular cluster systems of early-type cluster dwarf galaxies

Rory Smith, Ruben Sanchez-Janssen, Michael Fellhauer, Thomas H. Puzia, J. A. L. Aguerri, Juan-Pablo Farias

备注：
Accepted to MNRAS on 12/11/12, 16 pages, 11 figures
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摘要：

星系周围的球状星团系统（GCSs）的动力学常被用来估算总的封闭质量，甚至用来约束暗物质的分布。星系中的球状星团系统通常被认为是在宿主星系的势能范围内处于动力学平衡状态。然而，星系团受到一个快速发展，有时，暴力破坏性的潮汐场。利用数值模拟研究了扰动对早型星团矮星周围GCs动力学的影响。我们发现，GCS的动力学行为的强烈影响的束缚暗物质f_{DM}留在星系的分数。只有当f_{DM}下降到~ 15%时，恒星和GC才开始被剥离。即使当f_{DM}低至约3%时，观察到的GC速度分散仍然可以用于测量真实的封闭质量，其系数在2以内。这是可能的，部分原因是未结合的GC很快从星系体中分离出来。然而，即使是{ \it{bound} } GC的分布也可以在空间上扩展2-3倍。一旦f_{DM}落入<3%的状态，星系就接近完全分裂，GCS动力学不再能可靠地估计封闭的质量。在这种情况下，剩余的结合GCS可能在空间上扩展4至8倍。通过测量恒星盘的动力学，也许可以测试一个星系是否处于这种状态。我们证明，如果一个恒星盘旋转支持，它很可能是一个星系有足够的暗物质，动力学的GCS可以用来可靠地估计封闭的质量。

英文摘要：

The dynamics of globular cluster systems (GCSs) around galaxies are often used to assess the total enclosed mass, and even to constrain the dark matter distribution. The globular cluster system of a galaxy is typically assumed to be in dynamical equilibrium within the potential of the host galaxy. However cluster galaxies are subjected to a rapidly evolving and, at times, violently destructive tidal field. We investigate the impact of the harassment on the dynamics of GCs surrounding early type cluster dwarfs, using numerical simulations. We find that the dynamical behaviour of the GCS is strongly influenced by the fraction of bound dark matter f_{DM} remaining in the galaxy. Only when f_{DM} falls to ~15%, do stars and GCs begin to be stripped. Still the observed GC velocity dispersion can be used to measure the true enclosed mass to within a factor of 2, even when f_{DM} falls as low as ~3%. This is possible partly because unbound GCs quickly separate from the galaxy body. However even the distribution of {\it{bound}} GCs may spatially expand by a factor of 2-3. Once f_{DM} falls into the <3% regime, the galaxy is close to complete disruption, and GCS dynamics can no longer be used to reliably estimate the enclosed mass. In this regime, the remaining bound GCS may spatially expand by a factor of 4 to 8. It may be possible to test if a galaxy is in this regime by measuring the dynamics of the stellar disk. We demonstrate that if a stellar disk is rotationally supported, it is likely that a galaxy has sufficient dark matter, that the dynamics of the GCS can be used to reliably estimate the enclosed mass.

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