EFFECTS OF ANTENNA BEAM CHROMATICITY ON REDSHIFTED 21 cm POWER SPECTRUM AND IMPLICATIONS FOR HYDROGEN EPOCH OF REIONIZATION ARRAY
EFFECTS OF ANTENNA BEAM CHROMATICITY ON REDSHIFTED 21 cm POWER SPECTRUM AND IMPLICATIONS FOR HYDROGEN EPOCH OF REIONIZATION ARRAY
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DOI：
10.3847/0004-637x/825/1/9
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
N. Thyagarajan;A. Parsons;D. DeBoer;J. Bowman;A. Ewall-Wice;A. Neben;Nipanjana Patra
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文献类型：
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作者：
N. Thyagarajan;A. Parsons;D. DeBoer;J. Bowman;A. Ewall-Wice;A. Neben;Nipanjana Patra
前景和仪器的系统学无法解释，这严重限制了当前实验检测再电离时期（EoR）红移21 cm信号的灵敏度。即将进行的实验面临着一个挑战，即每个天线元件提供更多的收集面积，而不会降低系统学的数据。本文及其同伴表明，使用氢时代再电离阵列（HERA）作为一个例子，碟是可行的，以实现这种平衡。在这里，我们特别确定与天线功率模式相关的频谱系统学作为对所有EoR实验的重大损害，其导致已经明亮的前景功率泄漏远远超出理想限制并污染原本干净的EoR信号模式。这种色度的主要来源是天线馈电组件中以及相邻天线中的结构之间的反射。使用精确的前景模拟考虑到宽场效应，我们提供了一个通用的框架，以设置宇宙学动机的设计规范，这些反射，以防止进一步的EoR信号退化。我们表明，HERA将不会受到这种光谱系统学的阻碍，并证明，即使在一个保守的情况下，不执行前景删除，HERA将检测EoR信号的视线k模式，Mpc-1，具有很高的意义。在这些条件下，19单元HERA布局中的所有基线都能够在天空的大量观测窗口上探测EoR。
Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments from detecting redshifted 21 cm signals from the Epoch of Reionization (EoR). Upcoming experiments are faced with a challenge to deliver more collecting area per antenna element without degrading the data with systematics. This paper and its companions show that dishes are viable for achieving this balance using the Hydrogen Epoch of Reionization Array (HERA) as an example. Here, we specifically identify spectral systematics associated with the antenna power pattern as a significant detriment to all EoR experiments which causes the already bright foreground power to leak well beyond ideal limits and contaminate the otherwise clean EoR signal modes. A primary source of this chromaticity is reflections in the antenna-feed assembly and between structures in neighboring antennas. Using precise foreground simulations taking wide-field effects into account, we provide a generic framework to set cosmologically motivated design specifications on these reflections to prevent further EoR signal degradation. We show that HERA will not be impeded by such spectral systematics and demonstrate that even in a conservative scenario that does not perform removal of foregrounds, HERA will detect the EoR signal in line-of-sight k-modes, Mpc−1, with high significance. Under these conditions, all baselines in a 19-element HERA layout are capable of detecting EoR over a substantial observing window on the sky.