arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.06724astro-ph.GA
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银河系中央分子带的模拟-- I.气体动力学

Simulations of the Milky Way's central molecular zone -- I. Gas dynamics

Robin G. Tress, Mattia C. Sormani, Simon C. O. Glover, Ralf S. Klessen, Cara D. Battersby, Paul C. Clark, H Perry Hatchfield, Rowan J. Smith

摘要:

我们使用流体动力学模拟研究银河系的中央分子区(CMZ)。模拟包括非平衡化学网络、气体自引力、恒星形成和超新星反馈。我们解决的星际介质的结构在亚秒差距的分辨率,同时也捕捉CMZ和酒吧驱动的大规模流之间的相互作用,以$R\sim 5\kpc$。我们的主要发现如下:(1)文献中有时提出的内($R\lesssim120$ ~pc)和外($120\lesssim R\lesssim450$ ~pc)CMZ的区分是不必要的。相反,CMZ最好被描述为单一结构,即一个恒星形成环,外半径为$R\simeq 200$ ~pc,其中包括1.3 $^\circ$复合体,并直接与调节棒驱动流入的尘埃带相互作用。(2)这种吸积可以引起CMZ的平面外的显著倾斜。倾斜的CMZ可能为Molinari等人2011年在赫歇尔数据中发现的$\infty$形状的结构提供另一种解释。(3)在我们的模拟中的酒吧有效地驱动流入从银河系盘($R\simeq 3$ ~kpc)到CMZ($R\simeq200$ ~pc)的数量级为$1\rm\,M_\odot\,yr^{-1}$,与观测测定一致。(4)超新星反馈可以驱动从CMZ向内流向$\sim0.03\,\rm M_\odot\,yr^{-1}$量级的环核盘。(5)我们给出了一个新的解释的3D放置的20和50公里的$^{-1}$云,根据它们是接近($R\lesssim30$ ~pc)的银河系中心,但也连接到大规模的流在$R\gtrsim100$ ~pc。

英文摘要:

We use hydrodynamical simulations to study the Milky Way's central molecular zone (CMZ). The simulations include a non-equilibrium chemical network, the gas self-gravity, star formation and supernova feedback. We resolve the structure of the interstellar medium at sub-parsec resolution while also capturing the interaction between the CMZ and the bar-driven large-scale flow out to $R\sim 5\kpc$. Our main findings are as follows: (1) The distinction between inner ($R\lesssim120$~pc) and outer ($120\lesssim R\lesssim450$~pc) CMZ that is sometimes proposed in the literature is unnecessary. Instead, the CMZ is best described as single structure, namely a star-forming ring with outer radius $R\simeq 200$~pc which includes the 1.3$^\circ$ complex and which is directly interacting with the dust lanes that mediate the bar-driven inflow. (2) This accretion can induce a significant tilt of the CMZ out of the plane. A tilted CMZ might provide an alternative explanation to the $\infty$-shaped structure identified in Herschel data by Molinari et al. 2011. (3) The bar in our simulation efficiently drives an inflow from the Galactic disc ($R\simeq 3$~kpc) down to the CMZ ($R\simeq200$~pc) of the order of $1\rm\,M_\odot\,yr^{-1}$, consistent with observational determinations. (4) Supernova feedback can drive an inflow from the CMZ inwards towards the circumnuclear disc of the order of $\sim0.03\,\rm M_\odot\,yr^{-1}$. (5) We give a new interpretation for the 3D placement of the 20 and 50 km s$^{-1}$ clouds, according to which they are close ($R\lesssim30$~pc) to the Galactic centre, but are also connected to the larger-scale streams at $R\gtrsim100$~pc.

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