Determining the Nature of Late Gunn–Peterson Troughs with Galaxy Surveys
Determining the Nature of Late Gunn–Peterson Troughs with Galaxy Surveys
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DOI：
10.3847/1538-4357/aac2d6
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发表时间：
2017-08
期刊：
影响因子：
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通讯作者：
F. Davies;G. Becker;S. Furlanetto
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文献类型：
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作者：
F. Davies;G. Becker;S. Furlanetto
最近的观测已经在z∼5.5Ly∼森林中发现了长的(高达110Mpc/h)不透明的Gunn-Peterson槽，这是用后再电离星际介质的传统模型难以解释的。在这里，我们证明了对最深谷附近的星系群的观察可以区分这些特征的两种相互竞争的模型：由于电离光子平均自由路径的波动而电离背景较弱的深空洞将显示星系的不足，而延长的、不均匀的再电离引起的残余温度变化将显示星系的密度过高。我们使用这些相互竞争的解释的大型(∼550Mpc/h)半数值模拟来预测在z∼5.7时最大的已知低谷中的星系数量。我们量化了两个模型中Lyα有效光学厚度和星系表面密度的强相关性，并估计了现实测量可以测量这种相关性的程度。虽然光谱星系调查是理想的，但我们也表明，对Lyα发射星系的相对廉价的窄带调查有∼90%的可能性区分竞争模型。
Recent observations have discovered long (up to ∼110 Mpc/h), opaque Gunn–Peterson troughs in the z ∼ 5.5 Lyα forest, which are challenging to explain with conventional models of the post-reionization intergalactic medium. Here, we demonstrate that observations of the galaxy populations in the vicinity of the deepest troughs can distinguish two competing models for these features: deep voids where the ionizing background is weak due to fluctuations in the mean free path of ionizing photons would show a deficit of galaxies, while residual temperature variations from extended, inhomogeneous reionization would show an overdensity of galaxies. We use large (∼550 Mpc/h) semi-numerical simulations of these competing explanations to predict the galaxy populations in the largest of the known troughs at z ∼ 5.7. We quantify the strong correlation of Lyα effective optical depth and galaxy surface density in both models, and estimate the degree to which realistic surveys can measure such a correlation. While a spectroscopic galaxy survey is ideal, we also show that a relatively inexpensive narrowband survey of Lyα-emitting galaxies is ∼90% likely to distinguish between the competing models.