Kinematics of Galactic Centre clouds shaped by shear-seeded solenoidal turbulence
Kinematics of Galactic Centre clouds shaped by shear-seeded solenoidal turbulence
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由剪切种子螺线管湍流形成的银河中心云的运动学
DOI：
10.1093/mnras/stad2344
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发表时间：
2023
影响因子：
4.8
通讯作者：
Nogueras-Lara, Francisco
中科院分区：
文献类型：
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作者：
Petkova, Maya A.;Kruijssen, J. M. Diederik;Henshaw, Jonathan D.;Longmore, Steven N.;Glover, Simon C. O.;Sormani, Mattia C.;Armillotta, Lucia;Barnes, Ashley T.;Klessen, Ralf S.;Nogueras-Lara, Francisco
中央分子带（CMZ；银河系中心~500 pc）相对于银盘来说是一个运动学上不寻常的环境，具有高速色散和分子云的陡峭尺寸-线宽关系。此外，CMZ区域的恒星形成率（SFR）由于其大量致密气体而显着低于预期。解释低恒星形成率的一个重要因素是恒星形成气体的湍流状态，它似乎以旋转模式为主。然而，湍流驱动机制仍不清楚。在这项工作中，我们研究了银河引力势如何影响 CMZ 云中的湍流。我们关注 CMZ 云 G0.253+0.016（“砖块”），它非常静止，不太可能在运动学上受到恒星反馈的控制。我们证明了砖块的几个运动学特性在云尺度流体动力学模拟中自然产生，该模拟考虑了银河引力势。这些属性包括视线速度分布、陡峭的尺寸线宽关系以及湍流的主要螺线管性质。在模拟中，这些特性是由银河剪切力与云的引力塌缩相结合产生的。这有力地表明，银河引力势在塑造 CMZ 气体运动学方面起着至关重要的作用，并且是通过诱导主要螺线管湍流模式来抑制恒星形成率的主要因素。
The Central Molecular Zone (CMZ; the central ∼500 pc of the Galaxy) is a kinematically unusual environment relative to the Galactic disc, with high-velocity dispersions and a steep size–linewidth relation of the molecular clouds. In addition, the CMZ region has a significantly lower star formation rate (SFR) than expected by its large amount of dense gas. An important factor in explaining the low SFR is the turbulent state of the star-forming gas, which seems to be dominated by rotational modes. However, the turbulence driving mechanism remains unclear. In this work, we investigate how the Galactic gravitational potential affects the turbulence in CMZ clouds. We focus on the CMZ cloud G0.253+0.016 (‘the Brick’), which is very quiescent and unlikely to be kinematically dominated by stellar feedback. We demonstrate that several kinematic properties of the Brick arise naturally in a cloud-scale hydrodynamics simulation, that takes into account the Galactic gravitational potential. These properties include the line-of-sight velocity distribution, the steepened size–linewidth relation, and the predominantly solenoidal nature of the turbulence. Within the simulation, these properties result from the Galactic shear in combination with the cloud’s gravitational collapse. This is a strong indication that the Galactic gravitational potential plays a crucial role in shaping the CMZ gas kinematics, and is a major contributor to suppressing the SFR, by inducing predominantly solenoidal turbulent modes.