How Gas Accretion Feeds Galactic Disks
How Gas Accretion Feeds Galactic Disks
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DOI：
10.3847/1538-4357/ab0ec2
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
S. Ho;C. Martin;M. Turner
中科院分区：
文献类型：
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作者：
S. Ho;C. Martin;M. Turner
大量的观测表明，星系需要持续的气体供应来为恒星的形成提供燃料，并解释恒星的形成历史。然而，气体吸积的直接观测证据仍然很少。利用EAGLE宇宙流体力学模拟套件，研究了冷气体在星系中的吸积和冷气体运动学的观测特征。对于z=0.27时的EAGLE星系，我们发现冷气体以各向异性的方式聚集到星系中，典型的流入速度在20-60公里S−1之间。这些星系的质量流入速率和恒星形成速率大致相当，这意味着冷流入气体可能是维持星系恒星形成活动的原因。为了进一步将冷气体运动学与类星体视线观测的测量结果进行比较，我们选择了一个具有扩展的冷气体盘的Eagle星系，并使用模拟类星体视线探测了该冷气体。我们证明，通过观察星系盘的边缘，方位角小于10°的视线和60ppc的撞击参数可以探测到与星系盘旋转的冷气体。这个例子表明，延伸到光盘之外的冷气体盘可能解释了探测到星系主轴附近共转的冷气体的视线观测。
Numerous observations indicate that galaxies need a continuous gas supply to fuel star formation and explain the star formation history. However, direct observational evidence of gas accretion remains rare. Using the EAGLE cosmological hydrodynamic simulation suite, we study cold gas accretion onto galaxies and the observational signatures of the cold gas kinematics. For EAGLE galaxies at z = 0.27, we find that cold gas accretes onto galaxies anisotropically with typical inflow speeds between 20 and 60 km s−1. Most of these galaxies have comparable mass inflow rates and star formation rates, implying that the cold inflowing gas plausibly accounts for sustaining the star-forming activities of the galaxies. As motivation for future work to compare the cold gas kinematics with measurements from quasar sightline observations, we select an EAGLE galaxy with an extended cold gas disk, and we probe the cold gas using mock quasar sightlines. We demonstrate that by viewing the disk edge on, sightlines at azimuthal angles below 10° and impact parameters out to 60 pkpc can detect cold gas that corotates with the galaxy disk. This example suggests that cold gas disks extending beyond the optical disks possibly explain the sightline observations that detect corotating cold gas near galaxy major axes.