At redshifts beyond $z\gtrsim 30$, the 21 cm line from neutral hydrogen is expected to be essentially the only viable probe of the three-dimensional matter distribution. The lunar far-side is an extremely appealing site for future radio arrays that target this signal, as it is protected from terrestrial radio frequency interference, and has no ionosphere to attenuate and absorb radio emission at low frequencies (tens of MHz and below). We forecast the sensitivity of low-frequency lunar radio arrays to the bispectrum of the 21 cm brightness temperature field, which can in turn be used to probe primordial non-Gaussianity generated by particular early universe models. We account for the loss of particular regions of Fourier space due to instrumental limitations and systematic effects, and predict the sensitivity of different representative array designs to local-type non-Gaussianity in the bispectrum, parametrized by $f_{\mathrm{NL}}$. Under the most optimistic assumption of sample variance-limited observations, we find that $\sigma (f_{\mathrm{NL}})\lesssim 0.01$ could be achieved for several broad redshift bins at $z\gtrsim 30$ if foregrounds can be removed effectively. These values degrade to between $\sigma (f_{\mathrm{NL}})\sim 0.03$ and 0.7 for $z=30$ to $z=170$, respectively, when a large foreground wedge region is excluded.

This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades (part 2)’.

红移超过$z\gtrsim 30$，来自中性氢的 21 厘米线预计将是三维物质分布的唯一可行的探针。月球背面对于未来瞄准该信号的无线电阵列来说是一个极具吸引力的地点，因为它免受地面无线电频率干扰，并且没有电离层来衰减和吸收低频（数十兆赫及以下）无线电发射。我们预测了低频月球射电阵列对 21 厘米亮度温度场双谱的敏感性，这反过来又可以用来探测特定早期宇宙模型产生的原始非高斯性。我们考虑了由于仪器限制和系统效应而造成的傅立叶空间特定区域的损失，并预测了不同代表性阵列设计对双谱中局域型非高斯性的敏感性，参数化为$F_{\mathrm{荷兰}}$。在样本方差有限观测值的最乐观假设下，我们发现$\sigma （F_{\mathrm{荷兰}}）\lesssim 0.01$可以为几个广泛的红移箱实现$z\gtrsim 30$是否可以有效去除前景。这些值降级到$\sigma （F_{\mathrm{荷兰}}）～0.03$0.7 为$z=30$到$z=170$，分别是当排除大的前景楔形区域时。

本文是“月球天文学：未来几十年（第 2 部分）”讨论会议的一部分。