论文标题

使用小波散射变换对磁流失动力学模拟进行分类

Classification of Magnetohydrodynamic Simulations using Wavelet Scattering Transforms

论文作者

Saydjari, Andrew K., Portillo, Stephen K. N., Slepian, Zachary, Kahraman, Sule, Burkhart, Blakesley, Finkbeiner, Douglas P.

论文摘要

星际介质(ISM)中磁性水力学,重力和超音速湍流的复杂相互作用引入了非高斯结构,这可能会使理论与观察之间的比较复杂化。我们表明,小波散射变换(WST)与线性判别分析(LDA)结合使用,对2D ISM尘埃图中的非高斯结构敏感。 WST-LDA在我们的8个模拟测试台中,具有多达97 \%的真实正速率,对磁性水力动力学(MHD)的湍流模拟进行了分类,这些模拟具有不同的Sonic和AlfvénicMach数量。我们与其他两种非高斯表征,减少的小波散射变换(RWST)和3点相关函数(3PCF)进行了并排比较。我们还演示了3D-WST-LDA,并将其应用于位置位置 - 速度(PPV)空间中密度场的分类,其中可以使用速度相干性作为代理来研究密度相关性。 WST-LDA对于常见的观察伪影(例如条带和缺少数据)是可靠的,同时也足够敏感,足以提取净磁场方向以用于亚alfvénic湍流密度磁场。我们简要分析了点扩散函数和图像像素化对应用于密度场的2D-WST-LDA的影响,这为将WST-LDA应用于2D或3D All-Sky All-Sky防尘图的未来目标提供了信息。

The complex interplay of magnetohydrodynamics, gravity, and supersonic turbulence in the interstellar medium (ISM) introduces non-Gaussian structure that can complicate comparison between theory and observation. We show that the Wavelet Scattering Transform (WST), in combination with linear discriminant analysis (LDA), is sensitive to non-Gaussian structure in 2D ISM dust maps. WST-LDA classifies magnetohydrodynamic (MHD) turbulence simulations with up to a 97\% true positive rate in our testbed of 8 simulations with varying sonic and Alfvénic Mach numbers. We present a side-by-side comparison with two other methods for non-Gaussian characterization, the Reduced Wavelet Scattering Transform (RWST) and the 3-Point Correlation Function (3PCF). We also demonstrate the 3D-WST-LDA and apply it to classification of density fields in position-position-velocity (PPV) space, where density correlations can be studied using velocity coherence as a proxy. WST-LDA is robust to common observational artifacts, such as striping and missing data, while also sensitive enough to extract the net magnetic field direction for sub-Alfvénic turbulent density fields. We include a brief analysis of the effect of point spread functions and image pixelization on 2D-WST-LDA applied to density fields, which informs the future goal of applying WST-LDA to 2D or 3D all-sky dust maps to extract hydrodynamic parameters of interest.

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