SEEDING THE FORMATION OF COLD GASEOUS CLOUDS IN MILKY WAY-SIZE HALOS
SEEDING THE FORMATION OF COLD GASEOUS CLOUDS IN MILKY WAY-SIZE HALOS
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DOI：
10.1088/0004-637x/700/1/l1
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发表时间：
2009-05
期刊：
影响因子：
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通讯作者：
D. Keres̆;L. Hernquist
中科院分区：
文献类型：
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作者：
D. Keres̆;L. Hernquist
我们使用一个最高分辨率的宇宙学平滑粒子流体动力学模拟到目前为止，证明冷气体云形成银河系大小的星系。我们进一步探索机制负责其形成，并表明，大部分的云起源于晚时间的“冷模式”吸积的结果。在这里，仍然比周围的晕气体更冷和更密集的细丝不能直接连接到星系，因为它们在高红移时可以做到，而是容易受到冷却和瑞利-泰勒不稳定性的联合作用，在中间半径的晕内导致冷，致密的压力限制云的产生，没有相关的暗物质成分。热晕气体对进入的细丝的压缩以及晕积累期间的膨胀冲击有助于这一过程。与以前的模型不同，我们的机制直接从具有大量局部超密度的气体中播种云，并为云复合体的起源提供了一个通道。这些云稍后会“下雨”到星系上，为星星的形成提供燃料。由于相对较大的丝状体横截面和气体携带的净角动量，云将分布在星系周围的适度平坦区域。
We use one of the highest resolution cosmological smoothed particle hydrodynamic simulations to date to demonstrate that cold gaseous clouds form around Milky Way-size galaxies. We further explore mechanisms responsible for their formation and show that a large fraction of clouds originate as a consequence of late-time filamentary “cold mode” accretion. Here, filaments that are still colder and denser than the surrounding halo gas are not able to connect directly to galaxies, as they do at high redshift, but are instead susceptible to the combined action of cooling and Rayleigh–Taylor instabilities at intermediate radii within the halo leading to the production of cold, dense pressure-confined clouds, without an associated dark matter component. This process is aided through the compression of the incoming filaments by the hot halo gas and expanding shocks during the halo buildup. Our mechanism directly seeds clouds from gas with substantial local overdensity, unlike in previous models, and provides a channel for the origin of cloud complexes. These clouds can later “rain” onto galaxies, delivering fuel for star formation. Owing to the relatively large cross-section of filaments and the net angular momentum carried by the gas, the clouds will be distributed in a modestly flattened region around a galaxy.