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arXiv 0710.0182astro-ph
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主干合并遗迹中红、蓝球状星团的空间分布

The Spatial Distributions of Red and Blue Globular Clusters in Major Dry Merger Remnants

Min-Su Shin, Daisuke Kawata

备注：
Accepted version
发表信息：
Astrophys.J.691:83-90,2009
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摘要：

使用高分辨率的N体模拟，我们研究是否一个主要的干合并减轻红色和蓝色的球状星团（GC）之间的径向密度分布的差异。为此，我们研究了当密度分布用$n_{\rm GC}\propto r^{-α}$描述时，合并前体和合并残留物中GC密度斜率之间的关系。我们还研究了我们的结果如何依赖于合并轨道和初始GC密度分布的核心半径的大小。我们发现，一个主要的干合并，使GC的配置文件更平坦，和陡峭的初始GC配置文件导致更显着的平坦化，特别是如果初始斜率是陡峭的比$α\sim3.5$。我们的研究结果表明，如果有一个主要的干合并的椭圆星系的红色GC有一个陡峭的径向轮廓比蓝色GC，目前观察到的，和他们的斜率比$α\sim3.5$，两个人口之间的斜率差异变小后干合并。因此，观察到的红色和蓝色GC的斜率可以诊断干合并的重要性。目前的观测数据表明，在一些明亮的星系中，红色和蓝色GC具有更大的可比性和更浅的斜率，这可能表明它们经历了干合并。

英文摘要：

Using high-resolution N-body simulations, we examine whether a major dry merger mitigates the difference in the radial density distributions between red and blue globular clusters (GCs). To this end, we study the relation between the density slope of the GCs in merger progenitors and that in a merger remnant, when the density distribution is described by $n_{\rm GC}\propto r^{-α}$. We also study how our results depend on the merger orbit and the size of the core radius of the initial GC density distribution. We find that a major dry merger makes the GC profile flatter, and the steeper initial GC profile leads to more significant flattening, especially if the initial slope is steeper than $α\sim3.5$. Our result suggests that if there is a major dry merger of elliptical galaxies whose red GCs have a steeper radial profile than the blue GCs, as currently observed, and their slopes are steeper than $α\sim3.5$, the difference in the slopes between two populations becomes smaller after dry mergers. Therefore, the observed slopes of red and blue GCs can be a diagnostic of the importance of dry merger. The current observational data show that the red and blue GCs have more comparable and shallower slopes in some luminous galaxies, which may indicate that they have experienced dry mergers.

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