The first generation of star-forming haloes
The first generation of star-forming haloes
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DOI：
10.1111/j.1365-2966.2005.09416.x
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发表时间：
2005-04
影响因子：
4.8
通讯作者：
D. Reed;R. Bower;C. Frenk;Liang Gao;A. Jenkins;T. White;ICC-Durham;MPA-Garching;Antwerp
中科院分区：
文献类型：
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作者：
D. Reed;R. Bower;C. Frenk;Liang Gao;A. Jenkins;T. White;ICC-Durham;MPA-Garching;Antwerp
为了研究第一代恒星的形成，我们在高分辨率的N体模拟中建立了气体冷却模型。我们追踪了拉姆达冷暗物质（CDM）宇宙的一个区域，该区域特别被选为包含当今丰富的星系团。在这些太阳下质量分辨率模拟中形成的暗晕的性质在Gao等人的一篇配套论文中给出。当暗晕的质量为2.4 × 10 5 h −1 M.B yz 30时，第一个能够通过分子氢（H2）线发射冷却的气体云在极高的红移z 47处坍塌，大量的晕能够经历分子氢冷却，尽管它们形成恒星的能力取决于反馈过程的效率，例如离解莱曼-沃纳辐射。主晕的质量增长非常迅速，到z = 36时，其维里温度已达到10 - 4 K，此时气体冷却将被更有效的原子过程所主导。到z ≈ 30时，除非反馈过程阻止这样做，否则将形成一小群这样的潜在星系。通过这种红移，大质量（100 M ²）的第三族恒星能够将气体吸收到它们自己的宿主晕之外，邻近的H II区域可以渗透形成电离的超级气泡。这样的碎片会被分开得太远，在这个时候对再电离没有显著的贡献。在再电离前的宇宙中，早期冷却晕的数量密度很大，这提出了令人兴奋的前景，即这种超早期的恒星可能以伽马射线爆发或超新星的形式被观测到。Ke yw ords：方法：N体模拟-星系：形成-星系：晕-宇宙学：理论-暗物质。
We model gas cooling in high-resolution N-body simulations in order to investigate the formation of the first generation of stars. We follow a region of a Lambda cold dark matter (�CDM) universe especially selected to contain a rich cluster by the present day. The properties of the dark haloes that form in these subsolar mass-resolution simulations are presented in a companion paper by Gao et al. The first gas clouds able to cool by molecular hydrogen (H2)-line emission collapse at extremely high redshift, z ≈ 47, when the mass of the dark halo is 2.4 × 10 5 h −1 M� .B yz ≈ 30, a substantial population of haloes are capable of undergoing molecular hydrogen cooling although their ability to form stars is dependent on the efficiency of feedback processes such as dissociating Lyman‐Werner radiation. The mass of the main halo grows extremely rapidly and, by z ≈ 36, its virial temperature has reached 10 4 K, at which point gas cooling becomes dominated by more effective atomic processes. By z ≈ 30, a small ‘group’ of such potential galaxies will have formed unless prevented from doing so by feedback processes. By this redshift, massive (100 M � ) Population III stars are able to ionize gas well beyond their own host halo and neighbouring H II regions can percolate to form an ionized superbubble. Such patches would be too widely separated to contribute significantly to reionization at this time. The large number density of early cooling haloes in the pre-reionized universe raises the exciting prospect that this ultra-early generation of stars may be observable as gamma-ray bursts or supernovae. Ke yw ords: methods: N-body simulations ‐ galaxies: formation ‐ galaxies: haloes ‐ cosmology: theory ‐ dark matter.