再电离后21厘米强度测绘中的射电复合线污染
Radio Recombination Line Contamination in Post-Reionization 21 cm Intensity Mapping
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中文总结 AI 辅助
该研究探究再电离后21厘米强度测绘中的射电复合线污染，建立形式体系估算污染并预测红移下的功率谱污染，发现碳RRL贡献次要，污染振荡不会显著影响BAO的百分精度宇宙学测量。
中文摘要 AI 辅助
我们探究再电离后21厘米强度测绘观测中的射电复合线（RRL）污染。我们建立了一套形式体系，用于估算红移后进入21厘米图的大量RRL对21厘米自功率谱的污染，并预测所有红移下21厘米功率谱的污染情况。在z≲2时，Petrovic & Oh（2011）的保守上限模型外推预测21厘米功率谱会受到严重污染，而我们经经验校准的模型显示污染程度要小几个数量级。我们还估算了碳RRL的贡献，发现其占比次要。我们发现RRL污染在波数维度呈现高度振荡特性，这源于与21厘米发射源物理空间相近的RRL是主要污染源。这些振荡原则上可能会对重子声学振荡（BAO）导出的距离测量产生偏差，而BAO是再电离后21厘米强度测绘的关键科学驱动因素。我们发现BAO极值的偏移量比BAO用于百分精度宇宙学的相关偏移量至少小两个数量级。
英文摘要
We explore radio recombination line (RRL) contamination in post-reionization 21 cm intensity mapping observations. We develop a formalism to estimate the contamination of the 21 cm auto-power spectrum from the myriad of RRL lines that redshift into a 21 cm map and predict contamination of the 21 cm power spectrum at all redshifts. At $z\lesssim 2$, extrapolation of the conservative upper-bound model of Petrovic & Oh (2011) predicts high contamination to the 21 cm power spectrum, whereas our empirically-calibrated models suggest contamination several orders of magnitude smaller. We also estimate the contribution from carbon RRLs and find it to be subdominant. We find the RRL contamination is highly oscillatory in wavenumber, owing to the dominant contamination from RRLs emitted close in physical space to the 21 cm emission. These oscillations could in principle bias distance measurements derived from Baryon Acoustic Oscillations (BAO), a key science driver of post-reionization 21 cm intensity mapping. We find the shift in the BAO extrema is at least two orders of magnitude smaller than relevant for percent-precision cosmology from BAO.
