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arXiv 2104.05995astro-ph.GA
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恒星形成主序星上星系的气体含量、恒星形成和整体HI不对称性之间的关系

On the relationship between gas content, star-formation, and global HI asymmetry of galaxies on the star-forming main-sequence

Adam B. Watts, Barbara Catinella, Luca Cortese, Chris Power, Sara L. Ellison

摘要:

观测表明,星系中冷中性氢原子(HI)的扰动是普遍存在的,但这些扰动的原因仍然不清楚。虽然一些研究表明,在综合HI光谱(全球HI不对称性)是高HI丰富的系统,其他人声称,他们优先发现在HI贫困的星系。在这项工作中,我们利用的ALCAFA和xGASS调查,再加上合并后的星系的样本,澄清全球HI不对称性和气体性质的星系之间的联系。聚焦于ALCAFA中的恒星形成星系,我们发现,升高的全球HI不对称性与星系HI含量的变化无关,并且只有全球HI不对称性最高的星系才表现出比恒星形成率(sSFR)的小幅增加。然而,我们表明,缺乏一个趋势与HI含量是因为ALOFA错过了气体贫尾部的恒星形成的主序星。使用xGASS获得一个样本的恒星形成的星系,这是在sSFR和HI含量的代表,我们发现,全球HI非对称星系通常是更贫穷的气体比对称的在固定的恒星质量,在sSFR没有变化。我们的研究结果突出了星系属性和全球HI不对称性之间的连接的复杂性。这是进一步证实的事实,即使合并后的星系显示对称和不对称的HI光谱,表明合并活动并不总是导致一个不对称的全球HI光谱。

英文摘要:

Observations have revealed that disturbances in the cold neutral atomic hydrogen (HI) in galaxies are ubiquitous, but the reasons for these disturbances remain unclear. While some studies suggest that asymmetries in integrated HI spectra (global HI asymmetry) are higher in HI-rich systems, others claim that they are preferentially found in HI-poor galaxies. In this work, we utilise the ALFALFA and xGASS surveys, plus a sample of post-merger galaxies, to clarify the link between global HI asymmetry and the gas properties of galaxies. Focusing on star-forming galaxies in ALFALFA, we find that elevated global HI asymmetry is not associated with a change in the HI content of a galaxy, and that only the galaxies with the highest global HI asymmetry show a small increase in specific star-formation rate (sSFR). However, we show that the lack of a trend with HI content is because ALFALFA misses the gas-poor tail of the star-forming main-sequence. Using xGASS to obtain a sample of star-forming galaxies that is representative in both sSFR and HI content, we find that global HI asymmetric galaxies are typically more gas-poor than symmetric ones at fixed stellar mass, with no change in sSFR. Our results highlight the complexity of the connection between galaxy properties and global HI asymmetry. This is further confirmed by the fact that even post-merger galaxies show both symmetric and asymmetric HI spectra, demonstrating that merger activity does not always lead to an asymmetric global HI spectrum.

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