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arXiv 1809.04665astro-ph.COhep-ph
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河外星系的暗物质湮灭

Extragalactic Searches for Dark Matter Annihilation

Siddharth Mishra-Sharma

摘要:

我们正处于天体物理学和宇宙学数据驱动时代的黎明。大量正在进行和即将进行的实验,加上越来越开放的数据可用性方法,为解开宇宙中一些最深的谜团提供了巨大的潜力。其中之一是理解暗物质(DM)的性质--粒子物理学中未解决的主要问题之一。通过其天体物理特征来表征DM需要对其在天空中的分布有深入的了解,并使用新的统计方法。本论文的第一部分描述了一种新的统计技术的实现,该技术利用来自点源(PS)的光子的“clumpiness”来推导隐藏在天体物理数据集中的PS种群的属性。这适用于费米卫星在高纬度($|b| > 30$ °)的数据,以表征银河系外起源的PS的贡献。我们发现,大多数河外伽马射线发射可以归因于未解决的PS具有与已知的源,如活动星系核的属性一致。这就大大减少了暗物质贡献的空间。本论文的第二部分提出了一个问题:“在河外源中寻找湮灭暗物质的最佳途径是什么?”并试图通过构建一个管道来回答这个问题,该管道使用星系群目录来鲁棒地绘制银河系外暗物质的分布。这个框架,然后应用到费米数据和现有的集团目录,以寻找湮灭的暗物质在河外星系和星系团。

英文摘要:

We are at the dawn of a data-driven era in astrophysics and cosmology. A large number of ongoing and forthcoming experiments combined with an increasingly open approach to data availability offer great potential in unlocking some of the deepest mysteries of the Universe. Among these is understanding the nature of dark matter (DM)---one of the major unsolved problems in particle physics. Characterizing DM through its astrophysical signatures will require a robust understanding of its distribution in the sky and the use of novel statistical methods. The first part of this thesis describes the implementation of a novel statistical technique which leverages the "clumpiness" of photons originating from point sources (PSs) to derive the properties of PS populations hidden in astrophysical datasets. This is applied to data from the Fermi satellite at high latitudes ($|b| > 30$°) to characterize the contribution of PSs of extragalactic origin. We find that the majority of extragalactic gamma-ray emission can be ascribed to unresolved PSs having properties consistent with known sources such as active galactic nuclei. This leaves considerably less room for significant dark matter contribution. The second part of this thesis poses the question: "what is the best way to look for annihilating dark matter in extragalactic sources?" and attempts to answer it by constructing a pipeline to robustly map out the distribution of dark matter outside the Milky Way using galaxy group catalogs. This framework is then applied to Fermi data and existing group catalogs to search for annihilating dark matter in extragalactic galaxies and clusters.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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