Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function
Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function
复制标题
用金属丰度分布函数揭示被毁坏矮星系的质谱
DOI：
10.1093/mnras/stad535
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发表时间：
2023
影响因子：
4.8
通讯作者：
Deason A
中科院分区：
文献类型：
--
作者：
Deason A
聚积的恒星群是由被摧毁的星系的残余物组成的，通常主宰着银河系(MW)等星系的“恒星光环”。这一外部贡献者的集合是一个星系过去组装历史的关键指标。我们介绍了一种新的统计方法，它使用恒星群未入库的金属丰度分布函数(MDF)来估计其前体的质量谱。我们的模型利用了众所周知的星系质量-金属丰度关系，并假设单个前体的MDF为高斯分布：因此，总体MDF是来自较小星系的MDF的混合。我们将该方法应用于中波恒星晕以及经典的中波卫星星系。卫星星系的恒星成分样本规模相对较小，但我们没有发现任何证据表明l>；Lhost/100星系的数量增加。我们发现，MW星晕在10kpc内有∼1−3个大质量前体(L≳108L⊙)，总共可能有数百个前体。我们还对我们的方法进行了测试，发现我们的方法能够在2倍的范围内恢复真实的吸积星系群。未来的数据集将为MDFS提供更多数量级的恒星，这个方法可能是一种强大的技术，可以量化MW及其卫星的超微弱矮星质量尺度下的吸积星系群。
Accreted stellar populations are comprised of the remnants of destroyed galaxies, and often dominate the ‘stellar haloes’ of galaxies such as the Milky Way (MW). This ensemble of external contributors is a key indicator of the past assembly history of a galaxy. We introduce a novel statistical method that uses the unbinned metallicity distribution function (MDF) of a stellar population to estimate the mass spectrum of its progenitors. Our model makes use of the well-known mass–metallicity relation of galaxies and assumes Gaussian MDF distributions for individual progenitors: the overall MDF is thus a mixture of MDFs from smaller galaxies. We apply the method to the stellar halo of the MW, as well as the classical MW satellite galaxies. The stellar components of the satellite galaxies have relatively small sample sizes, but we do not find any evidence for accreted populations withL>Lhost/100. We find that the MW stellar halo hasN∼ 1−3 massive progenitors (L≳ 108L⊙) within 10 kpc, and likely several hundred progenitors in total. We also test our method on simulations of MW-mass haloes, and find that our method is able to recover the true accreted population within a factor of 2. Future data sets will provide MDFs with orders of magnitude more stars, and this method could be a powerful technique to quantify the accreted populations down to the ultra-faint dwarf mass scale for both the MW and its satellites.