The morphology of reionization in a dynamically clumpy universe
The morphology of reionization in a dynamically clumpy universe
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动态块状宇宙中再电离的形态
DOI：
10.1093/mnras/stad1057
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发表时间：
2023
影响因子：
4.8
通讯作者：
McQuinn, Matthew
中科院分区：
文献类型：
--
作者：
Cain, Christopher;D’Aloisio, Anson;Gangolli, Nakul;McQuinn, Matthew
最近对莱曼极限平均自由程（atz= 6）的测量表明，它可能非常短，这促使人们更好地理解电离光子汇在再电离中所起的作用。在再电离模拟中精确地模拟汇是具有挑战性的，因为如果104− 108 M的氘气结构贡献了显着的不透明度，则需要很大的动态范围。因此，对于汇在形成再电离形态中的重要性没有达成共识。我们解决这个问题，最近开发的辐射传输代码，其中包括一个动态的子网格模型的基础上辐射流体动力学模拟的汇。与假设一个完全压力平滑的星系际介质相比，我们的动力学处理在关于再电离源的典型假设下将电离泡的尺寸减小了。在再电离的中点附近，21 cm的功率在k = 0.1hMpc− 1时也同样降低。如果完全忽略压力平滑，这些影响比由较高的复合率引起的抑制要温和得多。汇是否在再电离的形态中起了重要作用取决于其源的性质。例如，如果再电离是由明亮的（MUV<-17）星系驱动的，即使忽略压力平滑，汇也会使大尺度21 cm功率降低至多20%。方便的是，当明亮的光源贡献显着，在我们的动态处理的形态可以准确地再现与均匀的子网格聚集因子，产生相同的电离光子预算。相比之下，如果MUV <$-13星系驱动再电离，则均匀聚集模型的误差可高达40%。
A recent measurement of the Lyman-limit mean free path atz= 6 suggests it may have been very short, motivating a better understanding of the role that ionizing photon sinks played in reionization. Accurately modelling the sinks in reionization simulations is challenging because of the large dynamic range required if ∼104−108M⊙gas structures contributed significant opacity. Thus, there is no consensus on how important the sinks were in shaping reionization’s morphology. We address this question with a recently developed radiative transfer code that includes a dynamical sub-grid model for the sinks based on radiative hydrodynamics simulations. Compared to assuming a fully pressure-smoothed intergalactic medium, our dynamical treatment reduces ionized bubble sizes byunder typical assumptions about reionization’s sources. Near reionization’s midpoint, the 21 cm power atk∼ 0.1hMpc−1is similarly reduced. These effects are more modest than thesuppression resulting from the higher recombination rate if pressure smoothing is neglected entirely. Whether the sinks played a significant role in reionization’s morphology depends on the nature of its sources. For example, if reionization was driven by bright (MUV< −17) galaxies, the sinks reduce the large-scale 21 cm power by at most 20 per cent, even if pressure smoothing is neglected. Conveniently, when bright sources contribute significantly, the morphology in our dynamical treatment can be reproduced accurately with a uniform sub-grid clumping factor that yields the same ionizing photon budget. By contrast, ifMUV∼ −13 galaxies drove reionization, the uniform clumping model can err by up to 40 per cent.