Satellite mass functions and the faint end of the galaxy mass–halo mass relation in LCDM
Satellite mass functions and the faint end of the galaxy mass–halo mass relation in LCDM
复制标题
卫星质量函数和 LCDM 中星系质量和晕质量关系的微弱末端
DOI：
10.1093/mnras/stac2057
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发表时间：
2022
影响因子：
4.8
通讯作者：
Navarro, Julio F.
中科院分区：
文献类型：
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作者：
Santos-Santos, Isabel M. E.;Sales, Laura V.;Fattahi, Azadeh;Navarro, Julio F.
最微弱星系的丰富程度让我们能够深入了解暗物质的本质和矮星系的形成过程。在 LCDM 情景中，低质量晕如此之多，以至于矮星形成的效率必须随着晕质量的减少而急剧下降，以适应本星系群中观测到的矮星和卫星的相对稀缺。这种衰落的本质包含了调节最微弱系统中星系形成开始的机制的重要线索。受到一些最新的 LCDM 宇宙流体动力学模拟的启发，我们在这里探索了微弱端恒星质量 (M*)-晕质量 (M200) 关系的两种可能模型。一种模型包括一个尖锐的质量阈值，低于该阈值就不会形成发光星系，正如预期的那样，如果星系形成仅在高于氢冷却极限的系统中进行的话。在第二个模型中，M* 尺度为 M200 的陡峭幂律，没有明确的截止，正如最近的半解析工作所表明的那样。尽管这两个模型预测的类银河系周围的卫星数量与当前的观测结果一致，但它们预测的超微弱矮星和孤立矮星系周围的卫星数量却截然不同。我们的结果说明了如何利用矮星周围的卫星质量函数来探测微弱端的 M*-M200 关系，并阐明在 LCDM 场景中决定哪些低质量晕“点亮”或保持黑暗的机制。
The abundance of the faintest galaxies provides insight into the nature of dark matter and the process of dwarf galaxy formation. In the LCDM scenario, low-mass haloes are so numerous that the efficiency of dwarf formation must decline sharply with decreasing halo mass in order to accommodate the relative scarcity of observed dwarfs and satellites in the Local Group. The nature of this decline contains important clues to the mechanisms regulating the onset of galaxy formation in the faintest systems. We explore here two possible models for the stellar mass (M*)–halo mass (M200) relation at the faint end, motivated by some of the latest LCDM cosmological hydrodynamical simulations. One model includes a sharp mass threshold below which no luminous galaxies form, as expected if galaxy formation proceeds only in systems above the hydrogen-cooling limit. In the second model,M*scales as a steep power law ofM200with no explicit cut-off, as suggested by recent semi-analytical work. Although both models predict satellite numbers around Milky Way-like galaxies consistent with current observations, they predict vastly different numbers of ultrafaint dwarfs and of satellites around isolated dwarf galaxies. Our results illustrate how the satellite mass function around dwarfs may be used to probe theM*–M200relation at the faint end and to elucidate the mechanisms that determine which low-mass haloes ‘light up’ or remain dark in the LCDM scenario.