AI 中文总结
该研究结合三维尘埃图与中性氢吸收数据，确定微尺度原子结构可能位于本地泡外，表征了本地星际介质性质，其方法可用于验证相关区域尘埃云的结构与性质。
AI 中文摘要
本地泡（LB）包含显著的内部结构，许多星际云位于其内部或边界上。通过观测脉冲星方向的原子中性氢（HI）吸收轮廓的时间变异性，已有研究表明部分HI结构表现出光学深度变化，这代表了微尺度原子结构（TSAS）。然而，这些结构的确切位置尚未明确，也无法在本地泡的形成与演化框架中理解其起源。我们使用三维尘埃图提取选定的4颗脉冲星视线方向（LOS）上的氢体积密度分布，尝试将各个密度分量与HI吸收光谱的高斯分量相关联，揭示了朝向B1929+10的TSAS可能位于本地泡之外。对比整个视线方向及三维尘埃图子体积上积分的柱密度图像，显示存在弥散与团块状结构的混合。利用视线方向上平均HI体积密度和最大总中性氢密度的估计值，我们分别对电离分数和热压力设定上下限，以表征每颗脉冲星方向上的本地星际介质（ISM）性质。我们结合HI吸收数据与三维尘埃数据的方法具有更广泛的应用潜力，尤其可用于验证本地泡及更远区域尘埃云的结构与性质。
英文摘要
The Local Bubble (LB) contains significant internal structure, with many interstellar clouds lying within or on its walls. By observing time variability of atomic neutral hydrogen (HI) absorption profiles in the direction of pulsars, it was suggested that some of the HI structures exhibit variations in optical depth representative of the tiny scale atomic structure (TSAS). However, the exact location of these structures has not been known and understanding their origin in the framework of LB formation and evolution has been impossible. We use three-dimensional dust maps to extract density profiles of the hydrogen volume density along the line-of-sight (LOS) to four selected pulsars. We attempt to correlate individual density components with the Gaussian components of the HI absorption spectra, revealing the TSAS towards B1929+10 likely lies outside of the LB. Comparing column density images integrated over the entire LOS and over sub-volumes of the 3D dust maps show a mixture of diffuse and clumpy structure. Using estimates of the mean HI volume density and maximum total neutral hydrogen density along the LOS, we place upper and lower limits on ionisation fraction and thermal pressure, respectively, to characterise the properties of the local ISM towards each pulsar. Our method of using HI absorption data in conjunction with three-dimensional dust data holds potential for broader applications, especially to validate the structures and properties of dust clouds in the LB and beyond.
CommentsAccepted for publication in the Publications of the Astronomical Society of Australia (PASA); 18 pages, 10 figures (two in appendix)
