The bispectrum is a three-point statistic with the potential to provide additional information beyond power spectra analyses of survey data sets. Radio telescopes that broadly survey the 21-cm emission from neutral hydrogen (H i) are a promising way to probe LSS and in this work we present an investigation into the H i intensity mapping (IM) bispectrum using simulations. We present a model of the redshift space H i IM bispectrum including observational effects from the radio telescope beam and 21-cm foreground contamination. We validate our modelling prescriptions with measurements from robust IM simulations, inclusive of these observational effects. Our foreground simulations include polarization leakage, on which we use a principal component analysis cleaning method. We also investigate the effects from a non-Gaussian beam including side-lobes. For a MeerKAT-like single-dish IM survey at z = 0.39, we find that foreground removal causes an $8{{\ \rm per\ cent}}$ reduction in the equilateral bispectrum’s signal-to-noise ratio, whereas the beam reduces it by $62{{\ \rm per\ cent}}$. We find our models perform well, generally providing $\chi ^2_\text{dof}\sim 1$, indicating a good fit to the data. Whilst our focus is on post-reionization, single-dish IM, our modelling of observational effects, especially foreground removal, can also be relevant to interferometers and reionization studies.

中文翻译：

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包含观测效应的 H i 强度映射双谱

双谱是一个三点统计，有可能提供超出调查数据集的功率谱分析的额外信息。广泛调查中性氢 (H i) 的 21 厘米发射的射电望远镜是探测 LSS 的一种有前途的方法，在这项工作中，我们使用模拟对 H i 强度映射 (IM) 双谱进行了调查。我们提出了一个红移空间 H i IM 双谱模型，包括射电望远镜光束的观测效应和 21 厘米前景污染。我们使用来自强大的 IM 模拟的测量值来验证我们的建模处方，包括这些观察效果。我们的前景模拟包括极化泄漏，我们使用主成分分析清洁方法。我们还研究了包括旁瓣在内的非高斯光束的影响。对于 z = 0.39 的类似 MeerKAT 的单碟 IM 调查，我们发现前景去除会导致等边双谱的信噪比降低 $8{{\ \rm per\ cent}}$，而光束会降低它降低了 $62{{\ \rm per\ cent}}$。我们发现我们的模型表现良好，通常提供 $\chi ^2_\text{dof}\sim 1$，表明与数据的拟合度很好。虽然我们的重点是再电离后的单碟 IM，但我们对观测效果（尤其是前景去除）的建模也可能与干涉仪和再电离研究相关。一般提供$\chi ^2_\text{dof}\sim 1$，表示对数据的拟合度很好。虽然我们的重点是再电离后的单碟 IM，但我们对观测效果（尤其是前景去除）的建模也可能与干涉仪和再电离研究相关。一般提供$\chi ^2_\text{dof}\sim 1$，表示对数据的拟合度很好。虽然我们的重点是再电离后的单碟 IM，但我们对观测效果（尤其是前景去除）的建模也可能与干涉仪和再电离研究相关。