arXiv 1601.050972016-01astro-ph.CO

用宇宙微波背景观测约束暗物质性质

Constraining dark matter properties with Cosmic Microwave Background observations

Daniel B. Thomas, Michael Kopp, Constantinos Skordis

备注：: 12 pages, 10 figures, 2 tables, updated to match the version published in ApJ
DOI：: 10.3847/0004-637X/830/2/155

摘要：

我们研究了暗物质的性质，由状态方程参数$w$和两个微扰广义暗物质（GDM）参数$c^2_s$（声速）和$c^2_\text{vis}$（粘度）参数化，如何受到现有宇宙学数据的约束，特别是普朗克2015年数据发布。我们发现，GDM参数是一致的零，并强烈约束，没有证据表明扩展的暗物质模型超出了冷暗物质（CDM）的范例。暗物质状态方程被限制在$99.7\%$置信水平的$-0.000896<w<0.00238$范围内，这比以前使用WMAP数据发现的约束强几倍。在$99.7\%$置信水平下，参数$c^2_s$和$c^2_\text{vis}$分别被约束为小于$3.21\times10^{-6}$和$6.06\times10^{-6}$。GDM参数的加入确实显著影响了几个$Λ$ CDM参数的误差条，特别是无量纲暗物质密度$ω_g$和导出的参数$σ_8$和$H_0$。这可以通过包含限制宇宙膨胀历史的数据来部分缓解。

英文摘要：

We examine how the properties of dark matter, parameterised by an equation of state parameter $w$ and two perturbative Generalised Dark Matter (GDM) parameters $c^2_s$ (the sound speed) and $c^2_\text{vis}$ (the viscosity), are constrained by existing cosmological data, particularly the Planck 2015 data release. We find that the GDM parameters are consistent with zero, and are strongly constrained, showing no evidence for extending the dark matter model beyond the Cold Dark Matter (CDM) paradigm. The dark matter equation of state is constrained to be within $-0.000896<w<0.00238$ at the $99.7\%$ confidence level, which is several times stronger than constraints found previously using WMAP data. The parameters $c^2_s$ and $c^2_\text{vis}$ are constrained to be less than $3.21\times10^{-6}$ and $6.06\times10^{-6}$ respectively at the $99.7\%$ confidence level. The inclusion of the GDM parameters does significantly affect the error bars on several $Λ$CDM parameters, notably the dimensionless dark matter density $ω_g$ and the derived parameters $σ_8$ and $H_0$. This can be partially alleviated with the inclusion of data constraining the expansion history of the universe.

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