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arXiv 1210.7616astro-ph.GAastro-ph.CO
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第一个物体和第一个星系的形成和辐射反馈

Formation and Radiative Feedback of First Objects and First Galaxies

Masayuki Umemura, Hajime Susa, Kenji Hasegawa, Tamon Suwa, Benoit Semelin

摘要:

首先,形成的第一个物体驱动的暗物质的高分辨率流体动力学模拟重温。结果表明,在暗物质尖点的帮助下,~ 10^4 M_sun的暗物质晕可以产生第一发光体。因此,第一个物体的质量比之前的预测小了大约两个数量级。这意味着在早期宇宙中形成的Pop III恒星的数量可能比迄今为止认为的要大得多。第二,利用辐射流体动力学模拟研究了第一类天体中光电离和光解离光子的反馈,证明了在10^5M_2太阳晕中可以形成多颗恒星。第三,利用光离解反馈研究了原始原恒星周围吸积盘的碎裂。结果表明,光解离能降低原恒星的质量吸积率。此外,小至0.8 M_sun的原恒星也可能在保持质量的情况下被抛射并演化,这可能是星系晕中的“真正的第一颗星”。最后,最先进的辐射流体动力学模拟进行调查的第一星系的内部电离和逃逸的电离光子。我们发现,即使在质量大于6* 10^9 M_sun的晕中,通过形成大质量恒星的紫外反馈也会提高逃逸分数,同时显著降低恒星形成率。这可能对宇宙再电离产生重大影响。

英文摘要:

First, the formation of first objects driven by dark matter is revisited by high-resolution hydrodynamic simulations. It is revealed that dark matter haloes of ~10^4M_sun can produce first luminous objects with the aid of dark matter cusps. Therefore, the mass of first objects is smaller by roughly two orders of magnitude than in the previous prediction. This implies that the number of Pop III stars formed in the early universe could be significantly larger than hitherto thought. Secondly, the feedback by photo-ionization and photo-dissociation photons in the first objects is explored with radiation hydrodynamic simulations, and it is demonstrated that multiple stars can form in a 10^5M_sun halo. Thirdly, the fragmentation of an accretion disk around a primordial protostar is explored with photo-dissociation feedback. As a result, it is found that the photo-dissociation can reduce the mass accretion rate onto protostars. Also, protostars as small as 0.8M_sun may be ejected and evolve with keeping their mass, which might be detected as "real first stars" in the Galactic halo. Finally, state-of-the-art radiation hydrodynamic simulations are performed to investigate the internal ionization of first galaxies and the escape of ionizing photons. We find that UV feedback by forming massive stars enhances the escape fraction even in a halo as massive as > 6* 10^9M_sun, while it reduces the star formation rate significantly. This may have a momentous impact on the cosmic reionization.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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