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arXiv 1302.5462astro-ph.CO
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暗物质湮灭能量输出及其对高z IGM的影响

Dark Matter annihilation energy output and its effects on the high-z IGM

Ignacio J. Araya, Nelson D. Padilla

备注：
23 pages, 12 figures, accepted for publication in MNRAS
发表信息：
MNRAS 445 (2014) 850-868
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摘要：

我们研究的情况下，DM自我湮灭，以评估其重要性作为一种能量注入机制，IGM一般，并在特定的DM晕的介质。我们认为热遗迹WIMP粒子的质量为10 GeV和1 TeV，我们详细分析了DM在$Λ$ CDM宇宙学的聚类特性，在所有层次上，从晕和它们的质量函数，subhaloes和DM密度分布在其中，考虑绝热收缩的SMBH的存在。然后，我们计算相应的能量输出，得出结论，DM湮灭不构成一个重要的反馈机制。我们还计算了DM湮灭对IGM温度和电离分数的影响，发现在z ~ 10处，假设能量吸收最大，对于1 TeV的WIMP，IGM温度可以提高到$6 \times 10^{-4}$，电离分数可以提高到10 K;对于10 GeV的WIMP，IGM温度可以提高到200 K，电离分数可以提高到$8 \times 10^{-3}$ .我们的结论是DM湮灭不能被视为一种替代的再电离方案。关于通过修改21 cm差分亮温信号（$δ$ Tb）来探测WIMP的可探测性，我们得出结论，质量为1 TeV的热遗迹WIMP不太可能单独从全球信号中被探测到，除非在30 MHz < $ν$ <35 MHz对应于40 < z < 46的频率范围内的1- 3 mK水平上。然而，10 GeV质量的WIMP可以在1- 3 mK的水平上在55 MHz < $ν$ <119 MHz的频率范围内检测到，对应于11 < z < 25，并且在1- 10 mK的水平上在30 MHz < $ν$ <40 MHz的频率范围内检测到，对应于35 < z < 46。

英文摘要：

We study the case of DM self annihilation, in order to assess its importance as an energy injection mechanism, to the IGM in general, and to the medium within particular DM haloes. We consider thermal relic WIMP particles with masses of 10GeV and 1TeV and we analyse in detail the clustering properties of DM in a $Λ$CDM cosmology, on all hierarchy levels, from haloes and their mass function, to subhaloes and the DM density profiles within them, considering adiabatic contraction by the presence of a SMBH. We then compute the corresponding energy output, concluding that DM annihilation does not constitute an important feedback mechanism. We also calculate the effects that DM annihilation has on the IGM temperature and ionization fraction, and we find that assuming maximal energy absorption, at z ~ 10, for the case of a 1TeV WIMP, the ionization fraction could be raised to $6 \times 10^{-4}$ and the temperature to 10K, and in the case of a 10GeV WIMP, the IGM temperature could be raised to 200K and the ionization fraction to $8 \times 10^{-3}$. We conclude that DM annihilations cannot be regarded as an alternative reionization scenario. Regarding the detectability of the WIMP through the modifications to the 21 cm differential brightness temperature signal ($δ$Tb), we conclude that a thermal relic WIMP with mass of 1TeV is not likely to be detected from the global signal alone, except perhaps at the 1-3mK level in the frequency range 30MHz < $ν$ < 35MHz corresponding to 40 < z < 46. However, a 10GeV mass WIMP may be detectable at the 1-3mK level in the frequency range 55MHz < $ν$ < 119MHz corresponding to 11 < z < 25, and at the 1-10mK level in the frequency range 30MHz < $ν$ < 40MHz corresponding to 35 < z < 46.

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