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arXiv 1301.6546astro-ph.CO
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通过Sunyaev-Zeldovich效应研究温热星系际介质对CMB各向异性的贡献

The contribution of the Warm-Hot Intergalactic Medium to the CMB anisotropies via the Sunyaev-Zeldovich effect

I. F. Suarez-Velásquez, J. P. Mücket, F. Atrio-Barandela

摘要:

宇宙流体动力学模拟预测,所有重子中有很大一部分处于温度在$10^{5}-10^{7}$ K范围内的轻度非线性结构中。由于气体是高度电离的,它可以通过宇宙微波背景辐射产生的温度各向异性来探测。我们完善我们以前的热Sunyaev-Zeldovich效应的估计,通过引入一个非多方的状态方程来模拟来自不同流体动力学模拟的温度-密度相图的冲击加热气体的温度分布。根据具体模型,康普顿化参数在$10^{-7}\le y_c \le 2\times 10^{-6}$范围内变化,与FIRAS上限兼容。这个幅度与一个简单的玩具模型一致,该模型用于估计电离气体细丝引起的平均效应。利用对数正态概率密度函数计算了WHIM灯丝产生的温度各向异性的关联函数和功率谱。对于宽范围的参数空间,辐射功率谱的最大幅度是在$\ell \approx 200-500$处的$(\ell+1)\ell C_{\ell}/2π=0.7-70(μK)^2$。该振幅与重子密度、哈勃常数和物质功率谱$σ_8$的振幅成比例,如$[(\ell+1)\ell C_\ell]_{\mathrm{max}}/2π\propto σ_8^{2.6}(Ω_b h)^2$。由于热Sunyaev-Zeldovich效应具有特定的频率依赖性,我们分析了用即将到来的普朗克数据检测该分量的可能性。

英文摘要:

Cosmological hydrodynamical simulations predict that a large fraction of all baryons reside within mildly non-linear structures with temperatures in the range $10^{5}-10^{7}$K. As the gas is highly ionized, it could be detected by the temperature anisotropies generated on the Cosmic Microwave Background radiation. We refine our previous estimates of the thermal Sunyaev-Zeldovich effect by introducing a non-polytropic equation of state to model the temperature distribution of the shock heated gas derived from temperature-density phase diagrams of different hydrodynamical simulations. Depending on the specific model, the Comptonization parameter varies in the range $10^{-7}\le y_c \le 2\times 10^{-6}$, compatible with the FIRAS upper limit. This amplitude is in agreement with a simple toy model constructed to estimate the average effect induced by filaments of ionized gas. Using the log-normal probability density function we calculate the correlation function and the power spectrum of the temperature anisotropies generated by the WHIM filaments. For a wide range of the parameter space, the maximum amplitude of the radiation power spectrum is $(\ell+1)\ell C_{\ell}/2π=0.7-70(μK)^2$ at $\ell \approx 200-500$. This amplitude scales with baryon density, Hubble constant and the amplitude of the matter power spectrum $σ_8$ as $[(\ell+1)\ell C_\ell]_{\mathrm{max}}/2π\propto σ_8^{2.6}(Ω_b h)^2$. Since the thermal Sunyaev-Zeldovich effect has a specific frequency dependence, we analyze the possibility of detecting this component with the forthcoming Planck data.

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