The gamma-ray-flux PDF from galactic halo substructure
The gamma-ray-flux PDF from galactic halo substructure
复制标题
银河晕子结构的伽马射线通量 PDF
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
M. Kamionkowski
中科院分区：
文献类型：
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作者：
Samuel C. K. Lee;S. Ando;M. Kamionkowski
最近发射的费米伽马射线太空望远镜的目标之一是银河系晕中暗物质湮灭或衰变产生的弥散伽马射线背景。N体模拟和理论论证表明，银河系晕中的暗物质可能聚集成子结构，而不是平滑分布。在这里，我们提出的伽玛射线通量的概率分布函数（PDF）作为探测子结构的银河系晕。我们计算这个PDF的晕子结构的唯象模型，并确定区域的子结构参数空间中的PDF可以区分从PDF的暗物质的平滑分布。原则上，PDF允许子结构的统计检测，即使不能检测到单个光晕。它也可以用来探测弱相互作用大质量粒子（WIMPs）在最小微晕质量尺度~M_∞上的亚结构。此外，它还可以提供一种测量子结构质量函数的方法。然而，假设一个典型的晕子结构模型和一个保守估计的扩散背景的分析表明，子结构PDF可能无法检测到的费米在特定情况下，WIMP是一个中性伴子的寿命。然而，对于大范围的子结构、WIMP湮灭和漫射背景模型，PDF分析可以提供子结构的清晰签名。
One of the targets of the recently launched Fermi Gamma-ray Space Telescope is a diffuse gamma-ray background from dark-matter annihilation or decay in the Galactic halo. N-body simulations and theoretical arguments suggest that the dark matter in the Galactic halo may be clumped into substructure, rather than smoothly distributed. Here we propose the gamma-ray-flux probability distribution function (PDF) as a probe of substructure in the Galactic halo. We calculate this PDF for a phenomenological model of halo substructure and determine the regions of the substructure parameter space in which the PDF may be distinguished from the PDF for a smooth distribution of dark matter. In principle, the PDF allows a statistical detection of substructure, even if individual halos cannot be detected. It may also allow detection of substructure on the smallest microhalo mass scales, ~ M_⊕, for weakly-interacting massive particles (WIMPs). Furthermore, it may also provide a method to measure the substructure mass function. However, an analysis that assumes a typical halo substructure model and a conservative estimate of the diffuse background suggests that the substructure PDF may not be detectable in the lifespan of Fermi in the specific case that the WIMP is a neutralino. Nevertheless, for a large range of substructure, WIMP annihilation, and diffuse background models, PDF analysis may provide a clear signature of substructure.