The Observed Properties of Dark Matter on Small Spatial Scales
The Observed Properties of Dark Matter on Small Spatial Scales
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DOI：
10.1086/518025
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发表时间：
2007-03
期刊：
影响因子：
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通讯作者：
R. Wyse;G. Gilmore
中科院分区：
文献类型：
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作者：
R. Wyse;G. Gilmore
我们提出了一个综合最近的光度和运动学数据的几个最暗物质占主导地位的星系，矮球状星系的卫星，并比较它们的星星集群。半光半径呈双峰分布，稳定的星星团总是小于~30 pc，而稳定的星系总是大于~120 pc。我们扩展了以前已知的观测关系，并解释它们在暗物质本身的一个更基本的对内在属性：暗物质形成核心质量分布，核心尺度长度大于约100 pc，并始终具有最大的中心质量密度在一个狭窄的范围内。dSph星系中的暗物质似乎是聚集在一起的，因此在恒星分布中有一个平均体积质量密度，其值非常低，小于约0.1 M <$pc-3（约5 GeV/c2 cm-3）。所有dSph的速度分散在其光分布的边缘相当于约15公里s-1的圆周速度。最大的中心暗物质密度是依赖于模型的，但可能有一个特征值（在半径为10 pc的体积上平均），对于有利的核心暗物质分布（它类似于平均值），或~60 M <$pc-3（约2 TeV/c2 cm-3），如果暗物质密度分布是尖形的。银河系嵌入在具有这些性质的暗物质晕中;没有观察到包含暗物质的较小系统。这些数值提供了关于暗物质主导形式的新信息。
We present a synthesis of recent photometric and kinematic data for several of the most dark matter dominated galaxies, the dwarf spheroidal Galactic satellites, and compare them to star clusters. There is a bimodal distribution in half-light radii, with stable star clusters always being smaller than ~30 pc, while stable galaxies are always larger than ~120 pc. We extend the previously known observational relationships and interpret them in terms of a more fundamental pair of intrinsic properties of dark matter itself: dark matter forms cored mass distributions, with a core scale length of greater than about 100 pc, and always has a maximum central mass density within a narrow range. The dark matter in dSph galaxies appears to be clustered such that there is a mean volume mass density within the stellar distribution which has the very low value of less than about 0.1 M☉ pc-3 (about 5 GeV/c2 cm-3). All dSph's have velocity dispersions at the edge of their light distributions equivalent to circular velocities of ~15 km s-1. The maximum central dark matter density derived is model dependent but is likely to have a characteristic value (averaged over a volume of radius 10 pc) of ~0.1 M☉ pc-3 for the favored cored dark mass distributions (where it is similar to the mean value), or ~60 M ☉ pc-3 (about 2 TeV/c2 cm-3) if the dark matter density distribution is cusped. Galaxies are embedded in dark matter halos with these properties; smaller systems containing dark matter are not observed. These values provide new information about the nature of the dominant form of dark matter.