Lyman-α transmission properties of the intergalactic medium in the CoDaII simulation
Lyman-α transmission properties of the intergalactic medium in the CoDaII simulation
复制标题
CoDaII 模拟中星际介质的 Lyman-α 传输特性
DOI：
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发表时间：
2020
影响因子：
4.8
通讯作者：
G. Yepes
中科院分区：
文献类型：
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作者：
M. Gronke;P. Ocvirk;C. Mason;J. Matthee;S. Bosman;J. Sorce;Joseph S W Lewis;K. Ahn;D. Aubert;Taha Dawoodbhoy;I. Iliev;P. Shapiro;G. Yepes
莱曼α (Lyα)发射星系在z > 6的丰度下降是一个强大的和常用的探测器来限制宇宙再电离的进程。我们使用CoDaII模拟，这是一种辐射流体动力学模拟，具有~ 94个移动Mpc边长的盒子，来计算z ~ 5.8到7的星系间介质（IGM）的Lyα透射特性。我们的结果主要证实了之前的研究，即我们发现Lyα的透射率随着红移而下降，并且视线与视线之间的变化很大。然而，由于最近在高红移处发现了蓝色Lyα峰，我们也分析了蓝色侧的IGM透射，结果显示蓝色透射在z > 6处迅速下降。这种低透射率不仅可以归因于中性区域的存在，还可以归因于电离区域内残留的中性氢，其密度甚至低至nHI ~ 10−9 cm−3（有时与运动学效应相结合）导致能见度显著降低。然而，我们发现在z ~ 7处朝向M1600AB ~ - 21星系的视线是足够透明的，可以透射蓝色的Lyα峰。我们在解释观测结果的背景下讨论我们的结果。
The decline in abundance of Lyman-α (Lyα) emitting galaxies at z ≳ 6 is a powerful and commonly used probe to constrain the progress of cosmic reionization. We use the CoDaII simulation, which is a radiation hydrodynamic simulation featuring a box of ∼94 comoving Mpc side length, to compute the Lyα transmission properties of the intergalactic medium (IGM) at z ∼ 5.8 to 7. Our results mainly confirm previous studies, i.e. we find a declining Lyα transmission with redshift and a large sightline-to-sightline variation. However, motivated by the recent discovery of blue Lyα peaks at high redshift, we also analyse the IGM transmission on the blue side, which shows a rapid decline at z ≳ 6 of the blue transmission. This low transmission can be attributed not only to the presence of neutral regions but also to the residual neutral hydrogen within ionized regions, for which a density even as low as nHI ∼ 10−9 cm−3 (sometimes combined with kinematic effects) leads to a significantly reduced visibility. Still, we find that $sim 1{{
m per cent}}$ of sightlines towards M1600AB ∼ −21 galaxies at z ∼ 7 are transparent enough to allow a transmission of a blue Lyα peak. We discuss our results in the context of the interpretation of observations.