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arXiv 1707.09787astro-ph.CO
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暗物质对M31 Gamma-Ray辐射可能贡献的多频分析

A Multi-frequency analysis of possible Dark Matter Contributions to M31 Gamma-Ray Emissions

Geoff Beck, Sergio Colafrancesco

摘要:

我们研究的可能性,暗物质(DM)的贡献,最近观察到的伽马射线光谱中看到的M31星系。特别是,我们申请限制弱相互作用的大质量粒子DM湮灭截面来自后发座星系团和网状II矮星系,以确定最大的流量贡献DM湮灭的M31伽马射线光谱和银河系中心。由于前者的数据范围有限,我们将M31和银河系中心光谱的能量范围限制在1至12 GeV之间,并包括在后者目标中观察到的高能伽马射线过剩。在这样做的时候,我们将利用费米-LAT数据为所有提到的目标,以及扩散无线电数据的后发座星系团。多目标策略使用昏迷和网状II来获得横截面的限制,以及多频率的数据,确保我们的结果是强大的对间接DM排放建模中固有的各种不确定性。我们的研究结果表明,当Navarro-Frenk-White(或较浅)径向密度分布假设,严重的约束可以施加在M31和银河系中心光谱的一部分,可以占DM,与最好的限制所产生的横截面的约束从后发座无线电数据和网状II伽马射线的限制。这些特殊的限制迫使所有的研究湮灭通道,以贡献1%或更少的总积分伽马射线通量内的M31和银河系中心的目标。相比之下,当假设Navarro-Frenk-White曲线收缩时,通量的10- 100%可归因于DM。这表明如何敏感DM的贡献,伽玛射线辐射的可能性,在星系的核心配置文件。

英文摘要:

We examine the possibility of a dark matter (DM) contribution to the recently observed gamma-ray spectrum seen in the M31 galaxy. In particular, we apply limits on Weakly Interacting Massive Particle DM annihilation cross-sections derived from the Coma galaxy cluster and the Reticulum II dwarf galaxy to determine the maximal flux contribution by DM annihilation to both the M31 gamma-ray spectrum and that of the Milky-Way galactic centre. We limit the energy range between 1 and 12 GeV in M31 and galactic centre spectra due to the limited range of former's data, as well as to encompass the high-energy gamma-ray excess observed in the latter target. In so doing, we will make use of Fermi-LAT data for all mentioned targets, as well as diffuse radio data for the Coma cluster. The multi-target strategy using both Coma and Reticulum II to derive cross-section limits, as well as multi-frequency data, ensures that our results are robust against the various uncertainties inherent in modelling of indirect DM emissions. Our results indicate that, when a Navarro-Frenk-White (or shallower) radial density profile is assumed, severe constraints can be imposed upon the fraction of the M31 and galactic centre spectra that can be accounted for by DM, with the best limits arising from cross-section constraints from Coma radio data and Reticulum II gamma-ray limits. These particular limits force all the studied annihilation channels to contribute 1% or less to the total integrated gamma-ray flux within both M31 and galactic centre targets. In contrast, considerably more, 10-100%, of the flux can be attributed to DM when a contracted Navarro-Frenk-White profile is assumed. This demonstrates how sensitive DM contributions to gamma-ray emissions are to the possibility of cored profiles in galaxies.

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