Gas infall and radial transport in cosmological simulations of milky way-mass discs
Gas infall and radial transport in cosmological simulations of milky way-mass discs
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银河系质量盘宇宙学模拟中的气体流入和径向传输
DOI：
10.1093/mnras/stab3251
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发表时间：
2021
影响因子：
4.8
通讯作者：
Wetzel, Andrew
中科院分区：
文献类型：
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作者：
Trapp, Cameron W.;Kereš, Dušan;Chan, Tsang Keung;Escala, Ivanna;Hummels, Cameron;Hopkins, Philip F.;Faucher-Giguère, Claude-André;Murray, Norman;Quataert, Eliot;Wetzel, Andrew
观测表明，在大而不透明的星系中，维持观测到的恒星形成速度需要持续的气体供应。为了促进恒星的形成，气体必须到达这些星系的内部区域。尽管气体对星系演化至关重要，但气体如何以及在哪里加入星系，在观测上受到的限制很小，而且很少在完全的宇宙模拟中进行探索。为了研究低红移星系附近的气体吸积，我们分析了4个银河系质量星系(MHALO∼1012M⊙)的FIRE-2宇宙学放大模拟，重点是宇宙线物理模拟。我们发现，在∼0时，气体以类似于气态圆盘边缘的角动量接近圆盘，并以较低的径向速度靠近圆盘，在边缘附近堆积，并稳定在完全旋转的支撑中。吸积的气体主要平行于圆盘移动，并在很大程度上在外围连接。在加入圆盘之前，轨迹平均会短暂地变得更加垂直。在圆盘内部，气体运动是复杂的，由螺旋臂诱导的振荡和反馈主导。然而，时间和方位向平均显示出缓慢的径向净流入，距离S−1的传输速度为1-3公里，通过∼M⊙yr−1的盘的净质量通量与星系的恒星形成速率相当，并随着气体沉入恒星形成而向银河系中心递减。在没有宇宙射线的模拟中(S−1，∼4-5⊙yr−1，1-7公里)，这些速率略高。我们发现我们的结果与观测限制总体上是一致的，并讨论了未来对星系内和星系周围气体流动的观测前景。
Observations indicate that a continuous supply of gas is needed to maintain observed star formation rates in large, discy galaxies. To fuel star formation, gas must reach the inner regions of such galaxies. Despite its crucial importance for galaxy evolution, how and where gas joins galaxies is poorly constrained observationally and rarely explored in fully cosmological simulations. To investigate gas accretion in the vicinity of galaxies at low redshift, we analyse the FIRE-2 cosmological zoom-in simulations for 4 Milky Way mass galaxies (Mhalo∼ 1012M⊙), focusing on simulations with cosmic ray physics. We find that atz∼ 0, gas approaches the disc with angular momentum similar to the gaseous disc edge and low radial velocities, piling-up near the edge and settling into full rotational support. Accreting gas moves predominately parallel to the disc and joins largely in the outskirts. Immediately prior to joining the disc, trajectories briefly become more vertical on average. Within the disc, gas motion is complex, being dominated by spiral arm induced oscillations and feedback. However, time and azimuthal averages show slow net radial infall with transport speeds of 1–3 km s−1and net mass fluxes through the disc of ∼M⊙yr−1, comparable to the galaxies’ star formation rates and decreasing towards galactic centre as gas is sunk into star formation. These rates are slightly higher in simulations without cosmic rays (1–7 km s−1, ∼4–5 M⊙yr−1). We find overall consistency of our results with observational constraints and discuss prospects of future observations of gas flows in and around galaxies.