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arXiv 0903.0413astro-ph.HEastro-ph.GAhep-ph
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Sommerfeld增强对暗物质湮灭的子结构增强

Substructure Boosts to Dark Matter Annihilation from Sommerfeld Enhancement

Jo Bovy

摘要:

最近引入的索末菲增强的暗物质湮灭截面的探测暗物质湮灭在星系晕的subhalos有重要的意义。除了这些次晕相对于主晕的高密度对暗物质湮灭截面的推动之外,索末菲增强导致的额外推动是因为它们在运动学上比星系晕更冷。如果我们进一步相信CDM的一般预测,在每个subhalo有一个丰富的子结构,这是近似自相似的星系晕,然后我表明,额外的推动来自这些小的子结构的密度增强和它们的小速度色散增强暗物质湮灭截面甚至进一步。我发现,非常大的提升因子($10^5$到$10^9$)是在一个大类的模型中获得的。这些助推因子对探测星系晕中矮球状星系的暗物质湮灭的影响是这样的,一般来说,它们比背景伽马射线通量更亮,可以被费米伽马射线太空望远镜探测到。

英文摘要:

The recently introduced Sommerfeld enhancement of the dark matter annihilation cross section has important implications for the detection of dark matter annihilation in subhalos in the Galactic halo. In addition to the boost to the dark matter annihilation cross section from the high densities of these subhalos with respect to the main halo, an additional boost caused by the Sommerfeld enhancement results from the fact that they are kinematically colder than the Galactic halo. If we further believe the generic prediction of CDM that in each subhalo there is an abundance of substructure which is approximately self-similar to that of the Galactic halo, then I show that additional boosts coming from the density enhancements of these small substructures and their small velocity dispersions enhance the dark matter annihilation cross section even further. I find that very large boost factors ($10^5$ to $10^9$) are obtained in a large class of models. The implications of these boost factors for the detection of dark matter annihilation from dwarf Spheroidal galaxies in the Galactic halo are such that, generically, they outshine the background gamma-ray flux and are detectable by the Fermi Gamma-ray Space Telescope.

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