论文标题
Gaskap-Hi试点调查科学III：小麦芽云中冷气的无偏见
GASKAP-HI Pilot Survey Science III: An unbiased view of cold gas in the Small Magellanic Cloud
论文作者
论文摘要
我们介绍了小麦芽云（SMC）中中性氢（HI）吸收的第一次无偏调查。该调查使用澳大利亚平方公里阵列探路者（ASKAP）望远镜作为银河ASKAP HI（GASKAP-HI）项目的一部分，使用了Pilot HI观察结果，其数据集已使用Gaskap-Hi吸收管道处理，此处也在此处进行描述。该数据集为229个连续源提供了吸收光谱，以前在SMC区域发表的连续源数量增加了275％，以及对SMC先前调查的吸收光谱质量的提高。我们的无偏见，结合了发射和吸收之间紧密匹配的光束尺寸，比2019年对SMC的ATCA调查较低的冷气派别（11％），并且更代表整个SMC。我们还发现，光学深度在SMC的条形区域和机翼区域之间变化很大。在栏中，我们发现光学深度通常很低（校正因子到$ \ Mathcal {r} _ {\ rm hi} \ sim 1.04 $的光学薄柱密度假设，但随列密度线性增加。然而，在机翼中，尽管色谱柱密度较差，但光学深度仍存在较大的散射。
We present the first unbiased survey of neutral hydrogen (HI) absorption in the Small Magellanic Cloud (SMC). The survey utilises pilot HI observations with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope as part of the Galactic ASKAP HI (GASKAP-HI) project whose dataset has been processed with the GASKAP-HI absorption pipeline, also described here. This dataset provides absorption spectra towards 229 continuum sources, a 275% increase in the number of continuum sources previously published in the SMC region, as well as an improvement in the quality of absorption spectra over previous surveys of the SMC. Our unbiased view, combined with the closely matched beam size between emission and absorption, reveals a lower cold gas faction (11%) than the 2019 ATCA survey of the SMC and is more representative of the SMC as a whole. We also find that the optical depth varies greatly between the SMC's bar and wing regions. In the bar we find that the optical depth is generally low (correction factor to the optically thin column density assumption of $\mathcal{R}_{\rm HI} \sim 1.04$) but increases linearly with column density. In the wing however, there is a wide scatter in optical depth despite a tighter range of column densities.
