红移21厘米功率谱中宽场特征的确认
Confirmation of Wide-Field Signatures in Redshifted 21 cm Power Spectra
摘要：
我们证实了我们最近的预测“干草叉”的前景签名在功率谱的高红移21厘米的测量干涉仪是敏感的大尺度结构的所有基线。这是由于宽视场仪器的固有响应，并且其特征在于来自邻近于被认为对宇宙学H I信号最敏感的那些模式的傅立叶模式中的前景发射的增强的功率。在我们最近的论文中，预测此特征的模拟中的许多签名都是针对Murchison Widefield Array（MWA）数据进行验证的，但这个关键的干草叉签名接近噪声水平。在本文中，我们提高了数据的灵敏度，通过相干平均12个独立的快照与相同的仪器设置，并提供了第一次确认的预测与信噪比> 10。这种宽场效应可以通过仔细的天线设计来减轻，以抑制地平线附近的灵敏度。为未来仪器（如氢时代再电离阵列和平方公里阵列）提出的天线孔径的简单模型表明，相对于MWA，它们应将干草叉的前景泄漏抑制约40 dB，并显着增加三维功率谱中这些临界傅立叶模式中宇宙学信号检测的可能性。
英文摘要：
We confirm our recent prediction of the "pitchfork" foreground signature in power spectra of high-redshift 21 cm measurements where the interferometer is sensitive to large-scale structure on all baselines. This is due to the inherent response of a wide-field instrument and is characterized by enhanced power from foreground emission in Fourier modes adjacent to those considered to be the most sensitive to the cosmological H I signal. In our recent paper, many signatures from the simulation that predicted this feature were validated against Murchison Widefield Array (MWA) data, but this key pitchfork signature was close to the noise level. In this paper, we improve the data sensitivity through the coherent averaging of 12 independent snapshots with identical instrument settings and provide the first confirmation of the prediction with a signal-to-noise ratio > 10. This wide-field effect can be mitigated by careful antenna designs that suppress sensitivity near the horizon. Simple models for antenna apertures that have been proposed for future instruments such as the Hydrogen Epoch of Reionization Array and the Square Kilometre Array indicate they should suppress foreground leakage from the pitchfork by ~40 dB relative to the MWA and significantly increase the likelihood of cosmological signal detection in these critical Fourier modes in the three-dimensional power spectrum.
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