LOFAR insights into the epoch of reionization from the cross-power spectrum of 21 cm emission and galaxies
LOFAR insights into the epoch of reionization from the cross-power spectrum of 21 cm emission and galaxies
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LOFAR 从 21 cm 发射和星系的互功率谱洞察再电离时代
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
S. Yatawatta
中科院分区：
文献类型：
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作者：
R. Wiersma;B. Ciardi;R. Thomas;G. Harker;S. Zaroubi;G. Bernardi;M. Brentjens;A. Bruyn;A. Bruyn;S. Daiboo;V. Jelić;S. Kazemi;L. Koopmans;P. Labropoulos;P. Labropoulos;O. Martinez;G. Mellema;A. Offringa;V. Pandey;V. Pandey;J. Schaye;V. Veligatla;H. Vedantham;S. Yatawatta;S. Yatawatta
通过结合 N 体模拟、半解析模型和辐射传输计算，我们估计了星系之间的理论交叉功率谱和再电离时期中性氢的 21 cm 发射量。根据之前的研究，我们发现21 cm发射最初在大尺度（≳30 Mpc）上与光晕相关，在中尺度（~5 Mpc）上反相关，在小尺度（≲3 Mpc）上不相关。随着再电离的进行，这种情况很快就会发生变化，并且两个场在大范围内变得反相关。互功率谱的归一化可用于对星际介质中的平均中性分数设置约束，其形状可以成为研究再电离拓扑的有力工具。当我们应用 drop-out 技术来选择星系并向 21 cm 信号添加低频阵列 (LOFAR) 望远镜预期的噪声时，我们发现虽然互功率谱的归一化仍然是探测再电离的有用工具，但其形状变得噪声太大而无法提供信息。另一方面，对于 Lyα 发射器 (LAE) 测量，互功率谱的归一化和形状都是合适的再电离探针。仔细观察使用 Subaru Hyper-Suprime Cam 的特定计划 LAE 观测计划，揭示了对计划红移处 21 厘米信号强度的担忧。如果 z 〜 7 处的电离分数低于此处估计的分数，则使用互功率谱可能是一种有用的练习，因为在较高的红移和中性分数下，它能够区分具有不同拓扑的两个玩具模型。
Using a combination of N-body simulations, semi-analytic models and radiative transfer calculations, we have estimated the theoretical cross-power spectrum between galaxies and the 21 cm emission from neutral hydrogen during the epoch of reionization. In accordance with previous studies, we find that the 21 cm emission is initially correlated with haloes on large scales (≳30 Mpc), anticorrelated on intermediate (˜5 Mpc) and uncorrelated on small (≲3 Mpc) scales. This picture quickly changes as reionization proceeds and the two fields become anticorrelated on large scales. The normalization of the cross-power spectrum can be used to set constraints on the average neutral fraction in the intergalactic medium and its shape can be a powerful tool to study the topology of reionization. When we apply a drop-out technique to select galaxies and add to the 21 cm signal the noise expected from the LOw Frequency ARray (LOFAR) telescope, we find that while the normalization of the cross-power spectrum remains a useful tool for probing reionization, its shape becomes too noisy to be informative. On the other hand, for an Lyα Emitter (LAE) survey both the normalization and the shape of the cross-power spectrum are suitable probes of reionization. A closer look at a specific planned LAE observing program using Subaru Hyper-Suprime Cam reveals concerns about the strength of the 21 cm signal at the planned redshifts. If the ionized fraction at z ˜ 7 is lower than the one estimated here, then using the cross-power spectrum may be a useful exercise given that at higher redshifts and neutral fractions it is able to distinguish between two toy models with different topologies.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.