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arXiv 1701.07005astro-ph.CO
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$\rm{21\, cm}$和$\rm{Ly}α$互相关的Halo模型方法

A Halo Model Approach to the $\rm{21\, cm}$ and $\rm{Ly}α$ Cross-correlation

Chang Feng, Asantha Cooray, Brian Keating

摘要:

我们提出了一个基于晕模型的方法来计算$\rm{21\,cm}$ HI强度波动和$\rm{Ly}α$发射体(LAE)在再电离时期(EoR)之间的互相关。暗物质晕周围的电离辐射被模拟为气泡,其大小和生长基于再电离光子的产生以及其他物理参数来确定。互相关显示出明显的负到正转变,与EoR期间星系际介质中从电离氢到中性氢的转变相关。互相关受到几种前景污染物的影响,包括对$\rm{21\,cm}$实验重要的前景无线电点源和对$\rm{Ly}α$实验重要的低$z$闯入者发射谱线,如$\rm{H}α$、OIII和OII.我们的计算表明,通过掩盖高通量的$\rm{Ly}α$测量,相关的前景污染的$\rm{21\,cm}$ - $\rm{Ly}α$互相关可以显着减少。我们预测了不同红移下$\rm{21\,cm}$ - $\rm{Ly}α$互相关的可探测性,并采用Fisher矩阵方法来估计EoR关键参数的不确定性,这些参数没有很好地受到其他再电离观测的约束。这种基于Halo模型的方法使我们能够快速探索不同$\rm{21\,cm}$和$\rm{Ly}α$实验的EoR参数空间。

英文摘要:

We present a halo-model-based approach to calculate the cross-correlation between $\rm{21\,cm}$ HI intensity fluctuations and $\rm{Ly}α$ emitters (LAE) during the epoch of reionization (EoR). Ionizing radiation around dark matter halos are modeled as bubbles with the size and growth determined based on the reionization photon production, among other physical parameters. The cross-correlation shows a clear negative-to-positive transition, associated with transition from ionized to neutral hydrogen in the intergalactic medium during EoR. The cross-correlation is subject to several foreground contaminants, including foreground radio point sources important for $\rm{21\,cm}$ experiments and low-$z$ interloper emission lines, such as $\rm{H}α$, OIII, and OII, for $\rm{Ly}α$ experiments. Our calculations show that by masking out high fluxes in the $\rm{Ly}α$ measurement, the correlated foreground contamination on the $\rm{21\,cm}$-$\rm{Ly}α$ cross-correlation can be dramatically reduced. We forecast the detectability of $\rm{21\,cm}$-$\rm{Ly}α$ cross-correlation at different redshifts and adopt a Fisher matrix approach to estimate uncertainties on the key EoR parameters that have not been well constrained by other observations of reionization. This halo-model-based approach enables us to explore the EoR parameter space rapidly for different $\rm{21\,cm}$ and $\rm{Ly}α$ experiments.

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