arXiv 2204.084812022-04-18astro-ph.GAphysics.comp-ph

球状星团从Milky Way卫星矮星系逃逸

The Escape of Globular Clusters from the Satellite Dwarf Galaxies of the Milky Way

Ali Rostami Shirazi, Hosein Haghi, Pouria Khalaj, Ahmad Farhani Asl, Akram Hasani Zonoozi

备注：: 16 pages, 7 figures (including 1 in the appendix), 6 tables (including 2 in the appendix). Accepted for publication in MNRAS
DOI：: 10.1093/mnras/stac1070

摘要：

利用数值模拟方法研究了银河系中球状星团从卫星矮球状星系逃逸的过程。我们开始跟随一个大样本的GC周围dSphs在MW势场的存在下的轨道。然后，我们得到的GCs离开他们的主机dSphs在哈勃时间内的分数。我们通过Hernquist密度分布对dSphs进行建模，其质量介于$10^7\,\mathrm{M}_{\odot}$和$7\times 10^9\,\mathrm{M}_{\odot}$之间。所有的dSphs都位于银盘平面上，但它们有不同的轨道偏心率和远星系距离。我们计算逃逸分数的GC从13个最大的dSphs的MW，使用它们的现实轨道周围的MW（由盖亚确定）。来自13 dSph的GC的逃逸分数在$12\%$至$93\%$的范围内。GC从这些dSphs中的平均逃逸时间小于8 $\,\mathrm{Gyrs}$，表明GC从dSphs中的逃逸过程已经结束。然后，我们采用了一组观测约束的密度分布的具体情况下的天炉座dSph。根据我们的结果，GCs的逃逸分数显示出负相关的质量和远星系距离的dSphs，以及正相关的轨道偏心率的dSphs。特别地，我们发现GCs从穹窿dSph的逃逸分数介于$13\%$和$38\%$之间。最后，我们观察到，当GC离开他们的主机dSphs，他们的最终轨道周围的MW没有太大的不同，从他们的主机dSphs。

英文摘要：

Using numerical simulations, we have studied the escape of globular clusters (GCs) from the satellite dwarf spheroidal galaxies (dSphs) of the Milky Way (MW). We start by following the orbits of a large sample of GCs around dSphs in the presence of the MW potential field. We then obtain the fraction of GCs leaving their host dSphs within a Hubble Time. We model dSphs by a Hernquist density profile with masses between $10^7\,\mathrm{M}_{\odot}$ and $7\times 10^9\,\mathrm{M}_{\odot}$. All dSphs lie on the Galactic disc plane, but they have different orbital eccentricities and apogalactic distances. We compute the escape fraction of GCs from 13 of the most massive dSphs of the MW, using their realistic orbits around the MW (as determined by Gaia). The escape fraction of GCs from 13 dSphs is in the range $12\%$ to $93\%$. The average escape time of GCs from these dSphs was less than 8 $\,\mathrm{Gyrs}$, indicating that the escape process of GCs from dSphs was over. We then adopt a set of observationally-constrained density profiles for specific case of the Fornax dSph. According to our results, the escape fraction of GCs shows a negative correlation with both the mass and the apogalactic distance of the dSphs, as well as a positive correlation with the orbital eccentricity of dSphs. In particular, we find that the escape fraction of GCs from the Fornax dSph is between $13\%$ and $38\%$. Finally, we observe that when GCs leave their host dSphs, their final orbit around the MW does not differ much from their host dSphs.

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英文摘要：

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