THE HYDROGEN EPOCH OF REIONIZATION ARRAY DISH. I. BEAM PATTERN MEASUREMENTS AND SCIENCE IMPLICATIONS
THE HYDROGEN EPOCH OF REIONIZATION ARRAY DISH. I. BEAM PATTERN MEASUREMENTS AND SCIENCE IMPLICATIONS
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DOI：
10.3847/0004-637x/826/2/199
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发表时间：
2016-02
期刊：
影响因子：
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通讯作者：
A. Neben;R. Bradley;J. Hewitt;D. DeBoer;A. Parsons;J. Aguirre;Z. Ali;Carina Cheng;A. Ewall-Wice;Nipanjana Patra;N. Thyagarajan;J. Bowman;R. Dickenson;J. Dillon;P. Doolittle;D. Egan;Mike Hedrick;D. Jacobs;S. Kohn;P. Klima;K. Moodley;B. Saliwanchik;Patrick Schaffner;J. Shelton;H. Taylor;R. Taylor;Max Tegmark;B. Wirt;Haoxuan Zheng
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文献类型：
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作者：
A. Neben;R. Bradley;J. Hewitt;D. DeBoer;A. Parsons;J. Aguirre;Z. Ali;Carina Cheng;A. Ewall-Wice;Nipanjana Patra;N. Thyagarajan;J. Bowman;R. Dickenson;J. Dillon;P. Doolittle;D. Egan;Mike Hedrick;D. Jacobs;S. Kohn;P. Klima;K. Moodley;B. Saliwanchik;Patrick Schaffner;J. Shelton;H. Taylor;R. Taylor;Max Tegmark;B. Wirt;Haoxuan Zheng
氢再电离时期射电阵列（HERA）是一个射电干涉仪，旨在探测中性氢再电离时期（EOR）的21 cm涨落功率谱。借鉴Murchison Widefield阵列和用于探测EOR的精密阵列的经验，HERA是一个具有悬挂偶极子馈电的大型（直径14 m）碟形天线的六边形阵列。碟盘不仅决定了干涉仪的灵敏度，而且影响了干涉仪中前景的观测频率结构。这是一系列四篇论文中的第一篇，通过模拟和测量来表征碟形天线的频率和角度响应。在本文中，我们专注于角响应（即，功率模式），其设置高延迟和低延迟的天空区域之间的相对权重，从而设置视在源频率结构。我们使用Neben等人的ORBCOMM光束映射系统测量了137 MHz的角响应。我们在最佳碟/馈源配置中测量了93 m2的收集面积，这意味着HERA-320应该检测z = 9处的EOR功率谱，噪声比为12.7，使用前景避免方法与单个季节的观察和74.3，使用前景减法方法。最后，我们研究了这些光束测量的前景在傅立叶空间中的分布的影响。
The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer aiming to detect the power spectrum of 21 cm fluctuations from neutral hydrogen from the epoch of reionization (EOR). Drawing on lessons from the Murchison Widefield Array and the Precision Array for Probing the EOR, HERA is a hexagonal array of large (14 m diameter) dishes with suspended dipole feeds. The dish not only determines overall sensitivity, but also affects the observed frequency structure of foregrounds in the interferometer. This is the first of a series of four papers characterizing the frequency and angular response of the dish with simulations and measurements. In this paper, we focus on the angular response (i.e., power pattern), which sets the relative weighting between sky regions of high and low delay and thus apparent source frequency structure. We measure the angular response at 137 MHz using the ORBCOMM beam mapping system of Neben et al. We measure a collecting area of 93 m2 in the optimal dish/feed configuration, implying that HERA-320 should detect the EOR power spectrum at z ∼ 9 with a signal-to-noise ratio of 12.7 using a foreground avoidance approach with a single season of observations and 74.3 using a foreground subtraction approach. Finally, we study the impact of these beam measurements on the distribution of foregrounds in Fourier space.