ESO 149- G003中的异常气体：一个MeerKAT-16视图
Anomalous gas in ESO 149-G003: A MeerKAT-16 View
摘要：
ESO 149-G 003是一个离我们很近的孤立矮不规则星系。ATCA以前的观测表明，存在偏离规则旋转圆盘运动学的异常中性氢（HI）。我们在16碟早期科学计划期间使用MeerKAT射电望远镜以及MeerLICHT光学望远镜进行了后续观测。我们更灵敏的射电观测证实了ESO 149-G 003中存在异常气体，并进一步证实了以前在星系中探测到的面外HI成分。采用一个简单的倾斜环模型，其中的运动学是确定只有四个参数，但包括形态不对称，我们重现星系的形态，这表明了高度的不对称性。通过比较我们的模型与观察到的HI，我们发现，在我们的模型中，我们不能占显着（但不占主导地位）的气体部分。从我们的模型和观察到的数据立方体之间的差异，我们估计，至少有7%-8%的HI在星系中表现出异常的运动学，而我们估计的最小质量分数小于1%的形态确认的面外组件。我们调查了一些全球的标度关系，并发现，除了气体占主导地位的中性气体与恒星的质量比为1.7，星系并没有表现出任何明显的全球性的特点。鉴于它的孤立性，正如光学观测所证实的那样，我们得出结论，该星系目前可能正在获得中性气体。它要么是重新吸积从星系中排出的气体，要么是吸积原始的星系际物质。
英文摘要：
ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous observations with the ATCA indicated the presence of anomalous neutral hydrogen (HI) deviating from the kinematics of a regularly rotating disc. We conducted follow-up observations with the MeerKAT radio telescope during the 16-dish Early Science programme as well as with the MeerLICHT optical telescope. Our more sensitive radio observations confirm the presence of anomalous gas in ESO 149-G003, and further confirm the formerly tentative detection of an extraplanar HI component in the galaxy. Employing a simple tilted-ring model, in which the kinematics is determined with only four parameters but including morphological asymmetries, we reproduce the galaxy's morphology, which shows a high degree of asymmetry. By comparing our model with the observed HI, we find that in our model we cannot account for a significant (but not dominant) fraction of the gas. From the differences between our model and the observed data cube we estimate that at least 7%-8% of the HI in the galaxy exhibits anomalous kinematics, while we estimate a minimum mass fraction of less than 1% for the morphologically confirmed extraplanar component. We investigate a number of global scaling relations and find that, besides being gas-dominated with a neutral gas-to-stellar mass ratio of 1.7, the galaxy does not show any obvious global peculiarities. Given its isolation, as confirmed by optical observations, we conclude that the galaxy is likely currently acquiring neutral gas. It is either re-accreting gas expelled from the galaxy or accreting pristine intergalactic material.
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