通过修改初始功率谱解决“大而不能倒”问题和空洞现象
Addressing the too-big-to-fail problem and the void phenomenon through a modified initial power spectrum
AI总结：
本文在偏移集理论框架下，提出在初始曲率功率谱小尺度添加高斯凸起，改变晕丰度与并合频率，以解决缺失卫星、TBTF问题和空洞现象。
摘要：
我们在半解析的偏移集理论（EST）框架内，研究了早期初始条件对非线性结构形成与演化的影响。分析表明，在小尺度上向初始曲率功率谱添加高斯凸起，会增加大质量晕的丰度，同时大幅减少小质量晕的数量，进而减少卫星星系。此外，该修改增加了主并合的频率，同时抑制了高质量比的小并合。这些特征可能为缺失卫星问题和“大而不能倒”（TBTF）问题提供解决方案。在欠密区域（即空洞）中，相同的修改增加了在空洞中发现嵌入的大质量晕的可能性，同时同样减少了小晕的数量，进而减少暗弱星系。这种行为暗示了对空洞现象的一种潜在解决方案，在空洞现象中，嵌入的晕尽管质量过大，但过于稀少而未被注意到。更准确地说，我们的结果表明，在高斯凸起中心附近的质量尺度上出现了大质量结构的过剩：$k_* = 1.85 \,\ m{h/Mpc}$ 和 $k_* = 3.95 \,\ m{h/Mpc}$。这些尺度分别对应于 $M_* = 10^{11}$ 和 $M_* = 10^{10}$ 的质量尺度。这一修改在更高质量尺度上延伸达两个数量级，同时将 $M_*$ 以下的晕丰度降低了两个至三个数量级。此外，我们发现演化条件、晕中晕以及特别是空洞中晕统计，可作为区分不同宇宙学模型的更灵敏且互补的探针。
英文摘要：
We investigate the impact of early-time initial conditions on nonlinear structure formation and evolution within the framework of the semi-analytical Excursion Set Theory (EST). Our analysis reveals that adding a Gaussian bump to the initial curvature power spectrum at small scales enhances the abundance of massive halos while sharply reducing the number of small-mass halos, and consequently, satellite galaxies. Moreover, this modification increases the frequency of major mergers while suppressing high-mass-ratio minor mergers. These features may offer resolutions to the missing satellite and Too Big to Fail (TBTF) problems. In underdense regions -- voids -- the same modifications increase the likelihood of finding massive halos embedded in voids while similarly decreasing the small-halo population, and consequently, faint galaxies. This behavior suggests a potential solution to the void phenomenon, in which embedded halos, despite being too massive, were too rare to be noticed. More precisely, our results indicate that an excess of massive structures emerges at mass scales near the center of the Gaussian bump: $k_* = 1.85 \,\rm{h/Mpc}$ and $k_* = 3.95 \,\rm{h/Mpc}$. These scales correspond to mass scales of $M_* = 10^{11}$ and $M_* = 10^{10}$, respectively. This modification extends up to two orders of magnitude in higher mass scales, while reducing the abundance of halos below $M_*$ by two to three orders of magnitude. Additionally, we find that evolutionary conditions, halo-in-halo, and particularly halo-in-void statistics serve as more sensitive and complementary probes for differentiating among cosmological models.
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