Dwarf stellar haloes: a powerful probe of small-scale galaxy formation and the nature of dark matter
Dwarf stellar haloes: a powerful probe of small-scale galaxy formation and the nature of dark matter
复制标题
矮恒星晕：小规模星系形成和暗物质本质的强大探测器
DOI：
10.1093/mnras/stab3524
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发表时间：
2022
影响因子：
4.8
通讯作者：
Deason A
中科院分区：
文献类型：
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作者：
Deason A
我们利用天体宇宙学模拟和经验星系模型研究了矮质量星系（与）的合并历史。我们的输入星系模型描述了恒星质量-光晕质量关系和星系占比。大合并和小合并的数量取决于暗物质的类型；特别是，在温暖的暗物质模型中，较小的合并被极大地抑制了。此外，恒星合并的数量很大程度上依赖于星系占据模型。例如，在星系形成的高质量阈值（即atz= 0）模型中，较小的合并对于恒星晕的增长是可以忽略不计的。此外，这个星系形成的阈值还可以决定卫星矮星和地矮星的恒星晕之间的相对差异（如果有的话）。通过对矮-矮合并的孤立模拟，我们表明，主要和次要合并的相对频率预测了非常不同的恒星晕：通常，“中等”暗物质合并比（约1:5）最大化了遥远恒星晕的增长。我们讨论了矮恒星晕的可观测性，并发现这些特征的表面亮度非常微弱。然而，当几颗矮星叠加在一起时，形成特别丰富的恒星晕的模型就可以被探测到。最后，我们表明，银河系晕中的恒星流与已知的矮卫星在相空间重叠，可能是它们剥离的恒星晕的残余物。仅仅是矮星晕的存在就已经对一些小规模模型造成了限制，因此观测探测器应该是优先考虑的问题。
We useN-body cosmological simulations and empirical galaxy models to study the merger history of dwarf-mass galaxies (with). Our input galaxy models describe the stellar mass–halo mass relation, and the galaxy occupation fraction. The number of major and minor mergers depends on the type of dark matter; in particular, minor mergers are greatly suppressed in warm dark matter models. In addition, the number of mergers that bring in stars is strongly dependent on the galaxy occupation model. For example, minor mergers are negligible for stellar halo growth in models with a high mass threshold for galaxy formation (i.e.atz= 0). Moreover, this threshold for galaxy formation can also determine the relative difference (if any) between the stellar haloes of satellite and field dwarfs. Using isolated simulations of dwarf–dwarf mergers, we show that the relative frequency of major and minor mergers predict very different stellar haloes: Typically, ‘intermediate’ dark matter merger ratios (∼1:5) maximize the growth of distant stellar haloes. We discuss the observability of dwarf stellar haloes and find that the surface brightness of these features are incredibly faint. However, when several dwarfs are stacked together, models that form particularly rich stellar haloes could be detectable. Finally, we show that stellar streams in the Galactic halo overlapping in phase space with known dwarf satellites are likely remnants of their stripped stellar haloes. The mere existence of dwarf stellar haloes can already put constraints on some small-scale models, and thus observational probes should be a high priority.