Inhomogeneous reionization of the intergalactic medium regulated by radiative and stellar feedbacks
Inhomogeneous reionization of the intergalactic medium regulated by radiative and stellar feedbacks
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辐射和恒星反馈调节的星际介质的不均匀再电离
DOI：
10.1046/j.1365-8711.2000.03365.x
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发表时间：
1999
影响因子：
4.8
通讯作者：
A. Jenkins
中科院分区：
文献类型：
--
作者：
B. Ciardi;A. Ferrara;F. Governato;A. Jenkins
我们研究了临界密度CDM宇宙中由恒星源（包括星族III天体）引起的非均匀再电离。源的空间分布是通过高分辨率数值n体模拟得到的。我们计算了源的性质，同时考虑了由大质量恒星调节的辐射（即电离和h2光解光子）和恒星（即SN爆炸）反馈的一致性处理。这使我们能够描述电离和解离区域在不同宇宙时代的拓扑结构，并推导出H， He和H2填充因子的演化，软紫外背景，宇宙恒星形成率和电离物体的最终命运。主要结果是：(i)星系间介质再电离z≈10（与气体凝聚因子有关），而H2在z≈25时已经完全解离；（ii）再电离主要是由质量较大的天体通过H线冷却坍缩引起的，而仅依靠H2冷却形成的天体不足以达到再电离的目的；（iii）当z≤15时，漫射软UV背景是辐射反馈效应的主要来源；在较高的z点，来自邻近物体的直接通量占主导地位；（iv）计算出的宇宙恒星形成历史与低红移观测到的吻合表明，重子转化为恒星的效率为≈1%；(v)我们发现在z≈8处存在大量不能形成恒星的暗天体。我们讨论并比较了我们的结果与类似的先前的研究。
We study the inhomogeneous reionization in a critical density CDM universe resulting from stellar sources, including Population III objects. The spatial distribution of the sources is obtained from high-resolution numerical N-body simulations. We calculate the source properties, taking into account a self-consistent treatment of both radiative (i.e. ionizing and H2-photodissociating photons) and stellar (i.e. SN explosions) feedbacks regulated by massive stars. This allows us to describe the topology of the ionized and dissociated regions at various cosmic epochs, and to derive the evolution of H, He and H2 filling factors, soft UV background, cosmic star formation rate and the final fate of ionizing objects. The main results are: (i) galaxies reionize the intergalactic medium by z≈10 (with some uncertainty related to the gas clumping factor), whereas H2 is completely dissociated already by z≈25; (ii) reionization is mostly caused by the relatively massive objects which collapse via H line cooling, while objects the formation of which relies on H2 cooling alone are insufficient for this purpose; (iii) the diffuse soft UV background is the major source of radiative feedback effects for z≤15; at higher z direct flux from neighbouring objects dominates; (iv) the match of the calculated cosmic star formation history with that observed at lower redshifts suggests that the conversion efficiency of baryons into stars is ≈1 per cent; (v) we find that a very large population of dark objects which failed to form stars is present by z≈8. We discuss and compare our results with similar previous studies.