Can the observed E/B ratio for dust galactic foreground be explained by sub-Alfvénic turbulence?
Can the observed E/B ratio for dust galactic foreground be explained by sub-Alfvénic turbulence?
复制标题
观测到的尘埃星系前景的 E/B 比可以用亚阿尔芬湍流来解释吗？
DOI：
10.1093/mnrasl/slx128
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发表时间：
2017
影响因子：
4.8
通讯作者：
D. Pogosyan
中科院分区：
文献类型：
--
作者：
D. Kandel;A. Lazarian;D. Pogosyan
最近普朗克对银河系尘埃偏振的观测表明，E模式的能量是B模式的两倍。Caldwell等人在磁流体动力学（MHD）湍流的背景下建立了一个理论模型，并发现解释这一结果存在问题。特别是，他们得出结论，有一个非常狭窄的理论参数范围可以解释观察结果。这就提出了一个问题，即对MHD湍流的公认描述是否适用于星际介质。我们重新审视了这个问题，并证明了MHD湍流对应于银河系高纬度范围内的马赫数，即$M_A\lesssim 0.5$，可以成功地解释$E$到$B$模态比的现有结果。
Recent Planck observations of dust polarization in the Galaxy have revealed that the power in $E$ mode is twice that in $B$ mode. Caldwell et. al. have formulated a theoretical model in the context of magnetohydrodynamic (MHD) turbulence and found it problematic to account for this result. In particular, they concluded that there is a very narrow range of theoretical parameters that could account for the observation. This poses a problem of whether the accepted description of MHD turbulence can apply to the interstellar medium. We revisit the problem and demonstrate that MHD turbulence corresponding to the high galactic latitudes range of Alfv\'en Mach numbers, i.e. $M_A\lesssim 0.5$, can successfully explain the available results for the $E$ to $B$ mode ratio.