文章基本信息

标题：Deep neutral hydrogen observations of Leo T with the Westerbork Synthesis Radio Telescope ★
本地全文：下载
作者：Elizabeth A. K. Adams ; Tom A. Oosterloo
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：612
DOI：10.1051/0004-6361/201732017
语种：English
出版社：EDP Sciences
摘要：Leo T is the lowest mass gas-rich galaxy currently known and studies of its gas content help us understand how such marginal galaxies survive and form stars. We present deep neutral hydrogen (HI) observations from the Westerbork Synthesis Radio Telescope in order to understand its HIdistribution and potential for star formation. We find a larger HIline flux than the previously accepted value, resulting in a 50% larger HImass of 4.1 × 105M⊙. The additional HIflux is from low surface brightness emission that was previously missed; with careful masking this emission can be recovered even in shallower data. We perform a Gaussian spectral decomposition to find a cool neutral medium component (CNM) with a mass of 3.7 × 104M⊙, or almost 10% of the total HImass. Leo T has no HIemission extending from the main HIbody, but there is evidence of interaction with the Milky Way circumgalactic medium in both a potential truncation of the HIbody and the offset of the peak HIdistribution from the optical center. The CNM component of Leo T is large when compared to other dwarf galaxies, even though Leo T is not currently forming stars and has a lower star formation efficiency than other gas-rich dwarf galaxies. However, the HIcolumn density associated with the CNM component in Leo T is low. One possible explanation is the large CNM component is not related to star formation potential but rather a recent, transient phenomenon related to the interaction of Leo T with the Milky Way circumgalactic medium.
关键词：Key wordsengalaxies: ISMgalaxies: dwarfLocal Groupradio lines: galaxiesgalaxies: individual: Leo Tgalaxies: star formation