The history of the baryon budget. Cosmic logistics in a hierarchical universe
The history of the baryon budget. Cosmic logistics in a hierarchical universe
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DOI：
10.1051/0004-6361:20053116
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发表时间：
2006
影响因子：
6.5
通讯作者：
Y. Rasera;R. Teyssier
中科院分区：
文献类型：
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作者：
Y. Rasera;R. Teyssier
利用一系列高分辨率的N体流体动力学数值模拟，我们研究了星系晕中重子收支演化的几种情况。我们导出了单个晕星星的形成历史（SFH），以及宇宙中的整体星星的形成率。我们开发了一个简单的分析模型，使我们能够计算出令人惊讶的准确预测，与我们的模拟相比，也与Springel & Hernquist（2003b）中提出的其他模拟相比。该模型依赖于两个主要参数：星星形成时间尺度t τ和风效率ηw。我们还计算，对于给定质量的晕，重子分数在以下每个阶段：冷盘气体，热晕气体和恒星。在这里，我们的分析模型预测与模拟结果吻合良好，如果一个正确地考虑到有限分辨率的影响。我们比较我们的分析模型的预测几个观测约束，并得出结论，一个非常窄的范围内的模型参数是允许的。银河风所发挥的重要作用概述，以及可能的“超级风”的情况下，集团和集群。我们的最佳模型在t = 3 Gyr和ηw = 1.5的情况下很好地再现了所观察到的SFH的“反分层”行为。在这种情况下，我们得到一个现今的宇宙重子预算为0.004，冷的0.0004，热的0.01和背的0.02（漫射背景）。
Using a series of high-resolution N-body hydrodynamical numerical simulations, we investigate several scenarios for the evolution of the baryon budget in galactic halos. We derive individual halo star formation history (SFH), as well as the global star formation rate in the universe. We develop a simple analytical model that allows us to compute surprisingly accurate predictions, when compared to our simulations, but also to other simulations presented in Springel & Hernquist (2003b). The model depends on two main parameters: the star formation time scale t∗ and the wind efficiencyηw. We also compute, for halos of a given mass, the baryon fraction in each of the following phases: cold discs gas, hot halo gas and stars. Here again, our analytical model predictions are in good agreement with simulation results, if one correctly takes into account finite resolution effect. We compare predictions of our analytical model to several observational constraints, and conclude that a very narrow range of the model parameters is allowed. The important role played by galactic winds is outlined, as well as a possible ‘superwind’ scenario in groups and clusters. The ‘anti-hierarchical’ behavior of observed SFH is well reproduced by our best model with t∗ = 3 Gyr and ηw = 1.5. We obtain in this case a present-day cosmic baryon budget of ∗ ≃ 0.004, cold ≃ 0.0004, hot ≃ 0.01 and back ≃ 0.02 (diffuse background).