论文标题
通过HI发射形态探测冷中性培养基，并随散射变换
Probing the cold neutral medium through HI emission morphology with the scattering transform
论文作者
论文摘要
中性氢（HI）发射表现出复杂的形态，可编码有关星际培养基（ISM）物理学的丰富信息。我们将散射变换（ST）应用于通过一组紧凑且可解释的系数来表征HI发射结构，并找到HI发射形态与HI冷中性介质（CNM）相位含量之间的连接。如果无法获得HI吸收测量值，通常通过光谱线分解来估计HI相结构。在这里，我们使用仅从HI发射空间信息得出的措施提出了CNM含量的第一个探针。我们将散射转换应用于高银河纬度（| b |> 30度）的Galfa-Hi数据，并将所得系数与来自档案中的HI发射和吸收光谱得出的CNM分数测量结果进行比较。我们量化了ST系数与测量的CNM馏分（FCNM）之间的相关性，并发现HI发射形态编码了大量的FCNM相关信息，并且针对小规模线性的基于ST的指标特别预测了FCNM。通过$ i_ {857}/n_ {hi} $比率增强较大的小规模线性测量，这进一步证实了这一点。这些结果与CNM含量较高的区域更加有小型丝状HI结构的群体相一致。我们的工作说明了HI形态和相位含量之间的物理联系，并建议通过使用HI光谱和空间信息来改善未来的相位分解方法。
Neutral hydrogen (HI) emission exhibits complex morphology that encodes rich information about the physics of the interstellar medium (ISM). We apply the scattering transform (ST) to characterize HI emission structure via a set of compact and interpretable coefficients, and find a connection between HI emission morphology and HI cold neutral medium (CNM) phase content. Where HI absorption measurements are unavailable, the HI phase structure is typically estimated from the emission via spectral line decomposition. Here we present the first probe of CNM content using measures solely derived from HI emission spatial information. We apply the scattering transform to GALFA-HI data at high Galactic latitudes (|b|>30 deg), and compare the resulting coefficients to CNM fraction measurements derived from archival HI emission and absorption spectra. We quantify the correlation between the ST coefficients and measured CNM fraction (fCNM), and find that HI emission morphology encodes substantial fCNM-correlating information, and that ST-based metrics for small-scale linearity are particularly predictive of fCNM. This is further corroborated by the enhancement of $I_{857}/N_{HI}$ ratio with larger ST measures of small-scale linearity. These results are consistent with the picture that regions with higher CNM content are more populated with small-scale filamentary HI structures. Our work illustrates a physical connection between HI morphology and phase content, and suggests that future phase decomposition methods can be improved by making use of both HI spectral and spatial information.
