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首页> 外文期刊>PASJ: Publications of the Astronomical Society of Japan >Environmental Effect on the Subhalo Abundance - a Solution to the Missing Dwarf Problem
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Environmental Effect on the Subhalo Abundance - a Solution to the Missing Dwarf Problem

机译：环境对亚卤盐丰度的影响-矮人缺失问题的解决方案

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Recent high-resolution simulations of the formation of dark-matter halos have shown that the distribution of subhalos is scale-free, in the sense that if scaled by the velocity dispersion of the parent halo, the subhalo velocity distribution functions of galaxy-sized and cluster-sized halos are identical. For cluster-sized halos, the simulation results agreed well with the observations. The simulations, however, predicted far too many subhalos for galaxy-sized halos. Our galaxy has several tens of known dwarf galaxies. On the other hand, simulated dark-matter halos contain thousands of subhalos. We performed a simulation of a single large volume, and measured the abundance of subhalos in all massive halos. We found that the variation of the subhalo abundance is very large, and those with the largest number of subhalos correspond to the simulated halos in previous studies. The subhalo abundance depends strongly on the local density of the background. Halos in high-density regions contain a large number of subhalos. Our Galaxy is in the low-density region. For our simulated halos in low-density regions, the number of subhalos is within a factor of four to that of our Galaxy. We argue that the "missing dwarf problem" is not a real problem, but is caused by biased selections of the initial conditions in previous studies, which were not appropriate for field galaxies.
机译：最近关于暗物质晕的形成的高分辨率模拟显示，亚晕的分布是无标度的，即如果通过母晕的速度色散进行标度，则银晕大小和簇大小的光环是相同的。对于星团大小的光环，模拟结果与观测结果吻合良好。然而，模拟预测对于银河系大小的光环而言，太多的亚晕。我们的星系有几十个已知的矮星系。另一方面，模拟的暗物质光环包含数千个亚晕。我们对单个大体积进行了模拟，并测量了所有大块晕中的亚晕的丰度。我们发现，亚晕的丰度变化非常大，而亚卤代数量最多的那些对应于先前研究中的模拟光晕。亚晕的丰度在很大程度上取决于背景的局部密度。高密度区域中的光晕包含大量的亚光晕。我们的银河系处于低密度区域。对于我们在低密度区域中模拟的光环，亚晕的数量是银河系的四分之一。我们认为“遗失矮人问题”不是一个真正的问题，而是由先前研究中对初始条件的选择不当造成的，这不适用于野外星系。

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