Detection of Molecular Gas in Void Galaxies : Implications for Star Formation in Isolated Environments
Detection of Molecular Gas in Void Galaxies : Implications for Star Formation in Isolated Environments
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空星系中分子气体的探测：对孤立环境中恒星形成的影响
DOI：
10.1088/0004-637x/815/1/40
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
S.
中科院分区：
文献类型：
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作者：
Das;M.; Saito;T.; Iono;D.; Honey;M.; Ramya;S.
我们提出了使用 CO (1-0) 线发射作为示踪剂来检测来自位于附近空隙的星系的分子气体。观测是使用野边山射电天文台的45 m单碟射电望远镜进行的。空虚星系位于宇宙中密度最低的部分，其中很大一部分是富含气体的晚期螺旋星系。尽管是孤立的，但它们仍在不断形成恒星，但与密度更大的环境中的星系相比，它们似乎正在缓慢演化。关于它们的恒星形成特性或冷气体含量知之甚少。在这项研究中，我们在五个虚空星系中寻找分子气体。这些星系是根据其相对较高的 IRAS 通量或 Hα 线光度来选择的，这两者都表明正在进行的恒星形成。所有五个星系似乎都是孤立的，其中两个位于牧夫座空洞内。我们检测到样本中五个星系中四个星系的 CO (1–0) 排放，它们的气体分子质量介于 10 8 和 10 9 M⊙ 之间。我们使用喜马拉雅钱德拉望远镜对三个探测到的星系进行了后续 Hα 成像观测，并根据 Hα 通量确定了它们的恒星形成率 (SFR)。 SFR 从 0.2 到 1 M⊙ yr− 1 变化；这与在本地星系中观察到的情况类似。我们的研究表明，虽然虚空星系位于密度较低的区域，但它们的盘中含有分子气体，并且具有与密度较高环境中的星系相似的恒星形成率。我们讨论我们的结果的含义。
We present the detection of molecular gas from galaxies located in nearby voids using the CO (1–0) line emission as a tracer. The observations were performed using the 45 m single dish radio telescope of the Nobeyama Radio Observatory. Void galaxies lie in the most underdense parts of our universe and a significant fraction of them are gas rich, late-type spiral galaxies. Although isolated, they have ongoing star formation but appear to be slowly evolving compared to galaxies in denser environments. Not much is known about their star formation properties or cold gas content. In this study, we searched for molecular gas in five void galaxies. The galaxies were selected based on their relatively high IRAS fluxes or Hα line luminosities, both of which signify ongoing star formation. All five galaxies appear to be isolated and two lie within the Bootes void. We detected CO (1–0) emission from four of the five galaxies in our sample and their molecular gas masses lie between 10 8 and 10 9 M⊙. We conducted follow-up Hα imaging observations of three detected galaxies using the Himalayan Chandra Telescope and determined their star formation rates (SFRs) from their Hα fluxes. The SFR varies from 0.2 to 1 M⊙ yr− 1; which is similar to that observed in local galaxies. Our study indicates that although void galaxies reside in underdense regions, their disks contain molecular gas and have SFRs similar to galaxies in denser environments. We discuss the implications of our results.