无标度宇宙学中的亚晕
Subhaloes in Scale-Free Cosmologies
摘要：
我们探索的依赖性的subhalo质量函数的线性物质功率谱的谱指数n使用无标度Einstein-de Sitter模拟与n=-1和n=-2.5。我们仔细考虑了有限体积效应，这可能会对先前的n<-2功率谱模拟提出质疑。使用6D朋友的朋友算法在源自高西格玛峰的所有晕中发现子晕。对于n=-1，我们发现，累积subhalo质量函数是独立的subhalo发现算法中使用的参数，并与LCDM模拟中发现的subhalo质量函数是一致的。特别地，次晕质量函数很好地符合指数为α =-0.9的幂律，即质量函数在次晕质量的每个对数间隔中具有大致相等的次晕质量。相反，对于n=-2.5，算法参数会影响次晕质量函数，因为次晕更具有三轴性，边界不太明确。我们发现，指数alpha通常较大，alpha>=-0.75。我们推断，虽然只要n>=-2，次晕质量函数似乎与n无关，但当n->-3时，它开始变平。因此，使用alpha=-1.0的常见做法可能会大大高估CDM层次结构中最小尺度下的subhaloes数量。
英文摘要：
We explore the dependence of the subhalo mass function on the spectral index n of the linear matter power spectrum using scale-free Einstein-de Sitter simulations with n=-1 and n=-2.5. We carefully consider finite volume effects that may call into question previous simulations of n<-2 power spectra. Subhaloes are found using a 6D friends-of-friends algorithm in all haloes originating from high-sigma peaks. For n=-1, we find that the cumulative subhalo mass function is independent of the parameters used in the subhalo finding algorithm and is consistent with the subhalo mass function found in LCDM simulations. In particular, the subhalo mass function is well fit by a power-law with an index of alpha=-0.9, that is the mass function has roughly equal mass in subhaloes per logarithmic interval in subhalo mass. Conversely, for n=-2.5, the algorithm parameters affect the subhalo mass function since subhaloes are more triaxial with less well defined boundaries. We find that the index alpha is generally larger with alpha>=-0.75. We infer that although the subhalo mass function appears to be independent of n so long as n>=-2, it begins to flatten as n->-3. Thus, the common practice of using alpha=-1.0 may greatly overestimate the number of subhaloes at the smallest scales in the CDM hierarchy.
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