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>Formation of the First Star Clusters and Massive Star Binaries by Fragmentation of Filamentary Primordial Gas Clouds
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Formation of the First Star Clusters and Massive Star Binaries by Fragmentation of Filamentary Primordial Gas Clouds
We perform a set of cosmological simulations of early structure formation incorporating baryonic streaming motions. We present a case where a significantly elongated gas cloud with ~104 solar mass (M ⊙) is formed in a pre-galactic (~107 M ⊙) dark halo. The gas streaming into the halo compresses and heats the massive filamentary cloud to a temperature of ~10,000 Kelvin. The gas cloud cools rapidly by atomic hydrogen cooling, and then by molecular hydrogen cooling down to ~400 Kelvin. The rapid decrease of the temperature and hence of the Jeans mass triggers fragmentation of the filament to yield multiple gas clumps with a few hundred solar masses. We estimate the mass of the primordial star formed in each fragment by adopting an analytic model based on a large set of radiation hydrodynamics simulations of protostellar evolution. The resulting stellar masses are in the range of ~50–120 M ⊙. The massive stars gravitationally attract each other and form a compact star cluster. We follow the dynamics of the star cluster using a hybrid N-body simulation. We show that massive star binaries are formed in a few million years through multi-body interactions at the cluster center. The eventual formation of the remnant black holes will leave a massive black hole binary, which can be a progenitor of strong gravitational wave sources similar to those recently detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).
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机译:我们执行了一组结合重子流运动的早期结构形成的宇宙学模拟。我们提出了这样一种情况,即在银河系前(约107 M⊙)的暗晕中形成了带有约104太阳质量(M⊙)的明显拉长的气体云。流进光环的气体将巨大的丝状云压缩并加热到约10,000开氏温度。气体云通过原子氢冷却迅速冷却,然后通过分子氢冷却降至约400开尔文。温度的快速下降以及由此导致的Jeans质量的迅速下降触发了灯丝的断裂,从而产生了多个具有数百个太阳质量的气体团块。我们通过采用基于大量星原演化的辐射流体动力学模拟的解析模型,估计每个碎片中形成的原始恒星的质量。产生的恒星质量在〜50–120 M range的范围内。巨大的恒星在重力作用下相互吸引,形成一个紧凑的恒星团。我们使用混合N体模拟跟踪恒星团的动力学。我们表明,通过星团中心的多体相互作用,在数百万年内形成了巨大的恒星双星。最终形成的残留黑洞将留下一个巨大的黑洞双星,这可能是强引力波源的祖先,类似于最近由高级激光干涉仪重力波天文台(LIGO)检测到的那些。
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