Title: Upper Limits on the 21 cm Power Spectrum at z = 5.9 from Quasar Absorption Line Spectroscopy Show Chinese title

Title: 在红移5.9处类星体吸收线光谱中21厘米功率谱的上限

Abstract: We present upper limits on the 21 cm power spectrum at $z = 5.9$ calculated from the model-independent limit on the neutral fraction of the intergalactic medium of $x_{\rm H{\small I }} < 0.06 + 0.05\ (1\sigma)$ derived from dark pixel statistics of quasar absorption spectra. Using 21CMMC, a Markov chain Monte Carlo Epoch of Reionization analysis code, we explore the probability distribution of 21 cm power spectra consistent with this constraint on the neutral fraction. We present 99 per cent confidence upper limits of $\Delta^2(k) < 10$ to $20\ {\rm mK}^2$ over a range of $k$ from 0.5 to $2.0\ h{\rm Mpc}^{-1}$, with the exact limit dependent on the sampled $k$ mode. This limit can be used as a null test for 21 cm experiments: a detection of power at $z=5.9$ in excess of this value is highly suggestive of residual foreground contamination or other systematic errors affecting the analysis. Show Chinese abstract

Abstract: 我们给出了在$z = 5.9$处的21厘米功率谱的上限，该上限是从类星体吸收光谱的暗像素统计得出的宇宙间中性分数的模型无关限制$x_{\rm H{\small I }} < 0.06 + 0.05\ (1\sigma)$计算得到的。 使用21CMMC，一种马尔可夫链蒙特卡罗再电离时期分析代码，我们探讨了与中性分数这一限制相一致的21厘米功率谱的概率分布。 我们给出了在$\Delta^2(k) < 10$到$20\ {\rm mK}^2$范围内，从0.5到$2.0\ h{\rm Mpc}^{-1}$的$k$范围内的99%置信度上限，具体的极限取决于采样的$k$模式。 此极限可作为21厘米实验的零假设检验：在$z=5.9$处检测到的功率超过此值高度暗示存在残留的前景污染或其他影响分析的系统误差。