Suppression of H2 Cooling in the Ultraviolet Background
Suppression of H2 Cooling in the Ultraviolet Background
复制标题
紫外背景下 H2 冷却的抑制
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Tom Abel
中科院分区：
文献类型：
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作者：
J. Wise;Tom Abel
在暗物质中通过分子氢冷却形成的和谐宇宙中的第一个发光物体控制着质量约为106M☉的光晕。我们使用欧拉自适应网格加密模拟来证明，在大的软紫外线辐射背景下，分子氢是主要的冷却剂。即使对于非常大的辐射背景，冷却和坍塌的晕质量也比通过原子氢线冷却冷却的晕小2个数量级。冷却晕的丰度和其中包含的宇宙质量分数与这个临界质量尺度成指数关系。因此，目前大多数的宇宙学再电离、化学演化、超大质量黑洞形成和星系形成的模型都低估了一个给定系统的恒星形成前身的数量。在红移最高的时候，这种分歧是最大的。我们还表明，即使在没有剩余电子的情况下，中心激波中的碰撞电离也会产生足够数量的电子来形成分子氢，并在远低于原子冷却极限的维里温度的晕圈中冷却气体。
The first luminous objects in the concordance cosmology form by molecular hydrogen cooling in dark matter dominated halos of masses ~106 M☉. We use Eulerian adaptive mesh refinement simulations to demonstrate that in the presence of a large soft ultraviolet radiation background, molecular hydrogen is the dominant coolant. Even for very large radiation backgrounds, the halo masses that cool and collapse are up to 2 orders of magnitude smaller than the halos that cool via atomic hydrogen line cooling. The abundance of cooling halos and the cosmic mass fraction contained within them depends exponentially on this critical mass scale. Consequently, the majority of current models of cosmological reionization, chemical evolution, supermassive black hole formation, and galaxy formation underestimate the number of star-forming progenitors of a given system by orders of magnitude. At the highest redshifts, this disagreement is largest. We also show that even in the absence of residual electrons, collisional ionization in central shocks create a sufficient amount of electrons to form molecular hydrogen and cool the gas in halos of virial temperatures far below the atomic cooling limit.