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arXiv 0905.1646astro-ph.CO
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室女星系团中球状星团的潮汐剥离

Tidal Stripping of Globular Clusters in the Virgo Cluster

Valeria Coenda, Hernan Muriel, Carlos J. Donzelli

备注：
Accepted to the Astrophysical Journal
发表信息：
Astrophys.J.700:1382-1390,2009
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摘要：

为了寻找球状星团潮汐剥离的证据，我们分析了从ACS室女星系团巡天中获得的13个椭圆星系的样本。这些星系属于室女星系团（VC）的主要集中区，目前的绝对星等为$-18.5<M_z<-22.5$。我们使用Jordán等人（2008）的公共GC目录，并根据其综合颜色将GC群体分为贫金属（蓝色）和富金属（红色）。星系的性质取自\citet{Peng:2008}。我们发现：1）总GC种群和蓝色GC种群的特定频率（$S_N$）作为投影星系距离$r_p$到M87的函数而增加。当使用三维距离$r_{3D}$时，观察到类似的结果。如果使用每个$10^9\Msun$（$T$）的GC数量进行分析，则发现相同的行为。与宿主星系的clustocentric距离的相关性被解释为GC剥离由于潮汐力的证据。2)主星系GC密度剖面的斜率与到室女座星系M87的距离没有相关性。3)我们还计算了9个样本星系中距星系中心超过$6.2 \kpc$的GC（$ρ_{out}$）的局域密度。我们发现，这些星系周围的GC人口主要是由蓝色GC。我们的研究结果表明，在大质量星系团中心附近的椭圆星系中观察到的蓝色和红色GC的数量和比例，可能与潜在的GC人口显着不同。这些差异可以用星系接近星系团中心时发生的潮汐剥离效应来解释。

英文摘要：

With the aim of finding evidence of tidal stripping of globular clusters (GCs) we analysed a sample of 13 elliptical galaxies taken from the ACS Virgo Cluster Survey (VCS). These galaxies belong to the main concentration of the Virgo cluster (VC) and present absolute magnitudes $-18.5<M_z<-22.5$. We used the public GC catalog of Jordán et al. (2008) and separated the GC population into metal poor (blue) and metal rich (red) according to their integrated colors. The galaxy properties were taken from \citet{Peng:2008}. We found that: 1) The specific frequencies ($S_N$) of total and blue GC populations increase as a function of the projected galaxy distances $r_p$ to M87. A similar result is observed when 3-dimensional distances $r_{3D}$ are used. The same behaviours are found if the analysis are made using the number of GCs per $10^9\Msun$ ($T$). The correlations with the clustocentric distance of the host galaxy are interpreted as evidence of GCs stripping due to tidal forces. 2) No correlation is found between the slope of GC density profiles of host galaxies and the galaxy distance to M87 (Virgo central galaxy). 3) We also computed the local density of GCs ($ρ_{out}$) located further than $6.2 \kpc$ from the galaxy center for nine galaxies of our sample. We find that the GC population around most of these galaxies is mainly composed of blue GCs. Our results suggest that the number and the fraction of blue and red GCs observed in elliptical galaxies located near the centers of massive clusters, could be significantly different from the underlying GC population. These differences could be explained by tidal stripping effects that occur as galaxies approach the centers of clusters.

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