ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. V. NEUTRAL GAS DYNAMICS AND KINEMATICS
ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. V. NEUTRAL GAS DYNAMICS AND KINEMATICS
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紫花苜蓿发现附近富含气体的矮星系狮子座 P.V. 中性气体动力学和运动学
DOI：
10.1088/0004-6256/148/2/35
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
J. Salzer
中科院分区：
文献类型：
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作者：
Elijah Z. Bernstein;J. Cannon;E. Elson;S. Warren;Jayaram Chengular;E. Skillman;E. Adams;A. Bolatto;R. Giovanelli;M. Haynes;K. McQuinn;S. Pardy;K. Rhode;J. Salzer
我们展示了金属极其贫乏的恒星形成矮不规则星系狮子座p的新H谱线图像。我们的H谱线图像探测了星际介质（ISM）的全局中性气体特性和局部条件。H - i形态沿光学长轴略微拉长。我们没有发现在大空间尺度上相互作用或气体流入的明显特征。中性气体盘呈现明显的旋转，但速度色散与旋转速度相当。估计旋转幅度为Vc =15±5 km s−1。在这些观测所探测到的H半径内，气体与恒星的质量比大约是2:1，而总质量与重子质量的比例是约15:1。我们利用这些信息将Leo P置于重子Tully-Fisher关系上，在迄今为止主要由矮球状星系占据的稀疏参数空间中测试宇宙结构的重子含量。我们在Leo P的中性ISM中检测到两个温度分量的特征；冷组分和暖组分的特征速度宽度分别为4.2±0.9 km s−1和10.1±1.2 km s−1，对应于动力学温度上限分别为~ 1100 K和~ 6200 K。冷H成分在物理分辨率为200pc时无法解析。在靠近单个氢离子区域的物理位置上观察到最高的氢离子表面密度。通过与其他金属极度缺乏星系（XMD）的中性气体性质的比较，我们发现，在所有已知的XMD星系中，Leo P的中性气体质量最低，其动力学质量比任何已知的金属丰度相当的XMD都要小两个数量级以上。
We present new H i spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H i images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H i morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be Vc =15 ± 5 km s−1. Within the H i radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully–Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s−1 and 10.1 ± 1.2 km s−1, corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H i component is unresolved at a physical resolution of 200 pc. The highest H i surface densities are observed in close physical proximity to the single H ii region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.