论文标题
灰尘的机械对齐（疯狂）I：在分形晶粒的旋转过程中，气盘漂移
The Mechanical Alignment of Dust (MAD) I: On the spin-up process of fractal grains by a gas-dust drift
论文作者
论文摘要
上下文：通常利用对齐的灰尘晶粒来探测磁场方向。但是，导致连贯的大规模谷物对齐的确切物理过程远非受到限制。目的：在这项工作中，我们旨在研究气盘漂移的影响，从而导致灰尘（疯狂）和灰尘极化的机械排列。方法：我们探索分形灰尘聚集体以统计分析不同谷物集合的平均比对行为。利用MC模拟确定了单个聚集体的旋转效率。分析了这些效率，以识别沿气盘漂移方向和磁场线方向晶粒对齐的稳定点。最后，根据谷物集合计算净灰尘极化。结果：CNM内的机械旋转足以将晶粒驱动到稳定的比对。可能的机械晶粒比对平行于漂移方向。所有谷物都可以在亚音速条件下对齐。在这里，我们预测疯狂的团结顺序具有两极分化效率。超音速漂移可能会导致迅速旋转，在这种旋转中，尘埃晶粒可能会在旋转上破坏，并且极化大大降低。在存在磁场的情况下，与纯MAD相比，拉长晶粒对齐所需的漂移大约要高一个数量级。在这里，尘埃极化效率为0.6-0.9，表明漂移可以提供探测磁场的先决条件。当漂移方向和磁场线的垂直方向时，对齐效率低下。结论：我们发现，必须将MAD视为一种替代驾驶机制，在该机制中，标准大鼠比对理论无法说明可用的灰尘极化观测值的全部范围。
Context: Aligned dust grains are commonly exploited to probe the magnetic field orientation. However, the exact physical processes that result in a coherent large-scale grain alignment are far from being constrained. Aims: In this work, we aim to investigate the impact of a gas-dust drift leading to a mechanical alignment of dust (MAD) and to dust polarization. Methods: We explore fractal dust aggregates to statistically analyze the average alignment behavior of distinct grain ensembles. The spin-up efficiencies for individual aggregates are determined utilizing MC simulations. These efficiencies are analyzed to identify stable points for the grain alignment in direction of the gas-dust drift and along the magnetic field lines. Finally, the net dust polarization is calculated per grain ensemble. Results: The mechanical spin-up within the CNM is sufficient to drive grains to a stable alignment. A likely mechanical grain alignment is parallel to the drift direction. All grains can align at subsonic conditions. Here, we predict a polarization efficiency in the order of unity for the MAD. A supersonic drift may result in a rapid rotation where dust grains may become rotationally disrupted and the polarization becomes drastically reduced. In the presence of a magnetic field, the drift required for the alignment of elongated grains is roughly one order of magnitude higher compared to the pure MAD. Here, the dust polarization efficiency is 0.6-0.9 indicating that a drift can provide the prerequisites to probe the magnetic field. The alignment is inefficient when the direction of the drift and the field lines are perpendicular. Conclusions: We find that MAD has to be taken into consideration as an alternative driving mechanism where the standard RAT alignment theory fails to account for the full spectrum of available dust polarization observations.
