Atlas3D项目- X。早型星系中分子和电离气体的起源
The Atlas3D project - X. On the origin of the molecular and ionised gas in early-type galaxies
摘要：
我们利用干涉CO和HI观测，光学积分场光谱探测起源的分子和电离星际介质（ISM）在本地早型星系（ETGs）。我们发现，36 \pm 5%的快速旋转的ETG样本的电离气体运动学不对准相对于恒星，设置一个强大的下限外部获得的气体的重要性（例如，从合并和冷吸积）。慢转子有一个平面分布的错位，表明气体的主要来源是外部的。在所有被探测到的星系中，分子、电离和原子气体总是在运动学上对齐的，即使它们与恒星不对齐，这表明ISM的所有这三个阶段都有一个共同的起源。此外，我们发现，在快速旋转ETG的冷，暖气体的起源是强烈的环境影响，尽管分子气体的检测率和质量分数是相当独立的组/集群成员。稠密星系团和室女星系团的分子气体几乎总是与恒星运动学一致，这与纯粹的内部起源一致。然而，在现场，恒星和气态成分之间的运动学失调表明，>46%的本地快速旋转ETG的气体来自外部来源。我们讨论了几种情况下，可以解释的环境二分法，但发现很难同时解释的运动失调的差异和恒定的检测率。此外，我们的研究结果表明，星系质量可能是与气体起源相关的一个重要的独立因素，在我们的样本中，质量最大的快速旋转星系（M_K<-24等;恒星质量>8x10^10 Msun）总是具有运动学排列的气体。（节略）
英文摘要：
We make use of interferometric CO and HI observations, and optical integral-field spectroscopy to probe the origin of the molecular and ionised interstellar medium (ISM) in local early-type galaxies (ETGs). We find that 36\pm5% of our sample of fast rotating ETGs have their ionised gas kinematically misaligned with respect to the stars, setting a strong lower limit on the importance of externally acquired gas (e.g. from mergers and cold accretion). Slow rotators have a flat distribution of misalignments, indicating that the dominant source of gas is external. The molecular, ionised and atomic gas in all the detected galaxies are always kinematically aligned, even when they are misaligned from the stars, suggesting that all these three phases of the ISM share a common origin. In addition, we find that the origin of the cold and warm gas in fast-rotating ETGs is strongly affected by environment, despite the molecular gas detection rate and mass fractions being fairly independent of group/cluster membership. Galaxies in dense groups and the Virgo cluster nearly always have their molecular gas kinematically aligned with the stellar kinematics, consistent with a purely internal origin. In the field, however, kinematic misalignments between the stellar and gaseous components indicate that >46% of local fast-rotating ETGs have their gas supplied from external sources. We discuss several scenarios which could explain the environmental dichotomy, but find it difficult to simultaneously explain the kinematic misalignment difference and the constant detection rate. Furthermore, our results suggest that galaxy mass may be an important independent factor associated with the origin of the gas, with the most massive fast-rotating galaxies in our sample (M_K<-24 mag; stellar mass of >8x10^10 Msun) always having kinematically aligned gas. (abridged)
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