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arXiv 2208.03312astro-ph.HEastro-ph.GAhep-ph
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Milky Way -大麦云系统的动力学如何影响gamma-ray对粒子暗物质的约束?

How do the dynamics of the Milky Way -- Large Magellanic Cloud system affect gamma-ray constraints on particle dark matter?

Christopher Eckner, Francesca Calore, Denis Erkal, Sophia Lilleengen, Michael S. Petersen

摘要:

以往对天体物理学暗物质(DM)约束的研究都假设银河系(MW)的DM晕可以孤立地建模。然而,最近的研究表明,MW最大的矮卫星,大麦云(LMC),质量是MW的10-20 $\%$,目前正在与我们的银河系合并。因此,MW和LMC的DM晕预计将强烈变形。在这里,我们解决和量化的动态响应所造成的间接DM搜索的前景通过MW的LMC的通道的影响。利用一组国家的最先进的数值模拟的MW-LMC系统的演变,我们得出的DM分布在这两个星系在目前的基础上的基函数展开形式主义。因此,我们建立$J$因子全天空地图的MW-LMC系统,以研究的影响,LMC通道上的伽马射线间接搜索热产生的DM湮灭的外MW晕以及内的LMC晕独立。我们进行了详细的分析,12年的费米-LAT数据,结合各种大规模的伽马射线发射组件,我们量化的系统不确定性与天体物理伽马射线源的不完善的知识。我们发现,由LMC通道所造成的动力学响应可以改变的速度平均湮灭截面的弱尺度粒子DM的水平相媲美的MW晕的密度分布和总质量的现有观测不确定性的约束。

英文摘要:

Previous studies on astrophysical dark matter (DM) constraints have all assumed that the Milky Way's (MW) DM halo can be modelled in isolation. However, recent work suggests that the MW's largest dwarf satellite, the Large Magellanic Cloud (LMC), has a mass of 10-20$\%$ that of the MW and is currently merging with our Galaxy. As a result, the DM haloes of the MW and LMC are expected to be strongly deformed. We here address and quantify the impact of the dynamical response caused by the passage of the LMC through the MW on the prospects for indirect DM searches. Utilising a set of state-of-the-art numerical simulations of the evolution of the MW-LMC system, we derive the DM distribution in both galaxies at the present time based on the Basis Function Expansion formalism. Consequently, we build $J$-factor all-sky maps of the MW-LMC system in order to study the impact of the LMC passage on gamma-ray indirect searches for thermally produced DM annihilating in the outer MW halo as well as within the LMC halo standalone. We conduct a detailed analysis of 12 years of Fermi-LAT data that incorporates various large-scale gamma-ray emission components and we quantify the systematic uncertainty associated with the imperfect knowledge of the astrophysical gamma-ray sources. We find that the dynamical response caused by the LMC passage can alter the constraints on the velocity-averaged annihilation cross section for weak scale particle DM at a level comparable to the existing observational uncertainty of the MW halo's density profile and total mass.

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