The Redshifted 21 cm Signal in the EDGES Low-band Spectrum
The Redshifted 21 cm Signal in the EDGES Low-band Spectrum
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EDGES 低频带频谱中的红移 21 cm 信号
DOI：
10.3847/1538-4357/ab2879
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
R. Subrahmanyan
中科院分区：
文献类型：
--
作者：
Saurabh Singh;R. Subrahmanyan
EDGES合作报告了在78 MHz的无线电背景中意外的深度吸收，并将其解释为第一次检测到来自宇宙黎明（CD）的红移21 cm信号。我们尝试通过采用最大平滑函数方法来建模前景的替代分析。使用这样的函数与平坦的吸收曲线一起对光谱进行联合拟合，得到921 ± 35 mK的最佳拟合吸收幅度。由EDGES分析推断的21 cm吸收深度需要调用非标准宇宙学，或新的物理学，或CD的新来源，这种与公认模型的紧张关系因我们的分析而加剧，表明吸收深度更大。或者，假设存在残留的未建模系统正弦特征，则测量的光谱可能同样拟合良好，并且我们通过检查额外的21 cm信号来进一步探索这种可能性。然后，数据支持具有振幅133 ± 60 mK的高斯模型参数的吸收，半功率处的最佳宽度为9 ± 3 MHz，中心频率为72.5 ± 0.8 MHz。我们还检查了测量光谱与合理的红移21 cm模型的一致性：在Cohen等人的全球21 cm图谱中，265个轮廓中的3个轮廓受到光谱的青睐。我们的结论是，EDGES数据可能是符合标准的宇宙学和天体物理学，没有调用多余的无线电背景或重子暗物质相互作用。
The EDGES collaboration reported an unexpectedly deep absorption in the radio background at 78 MHz and interpreted the dip as the first detection of a redshifted 21 cm signal from cosmic dawn (CD). We attempt an alternate analysis by adopting a maximally smooth function approach to model the foreground. A joint fit to the spectrum using such a function together with a flattened absorption profile yields a best-fit absorption amplitude of 921 ± 35 mK. The depth of the 21 cm absorption inferred by the EDGES analysis required invoking nonstandard cosmology, or new physics, or new sources at CD, and this tension with accepted models is compounded by our analysis that suggests absorption of greater depth. Alternatively, the measured spectrum may be equally well fit assuming there exists a residual unmodeled systematic sinusoidal feature, and we explore this possibility further by examining for additional 21 cm signal. The data then favor an absorption with Gaussian model parameters of amplitude 133 ± 60 mK, best width at half-power 9 ± 3 MHz, and center frequency 72.5 ± 0.8 MHz. We also examine the consistency of the measured spectrum with plausible redshifted 21 cm models: a set of 3 of the 265 profiles in the global 21 cm atlas of Cohen et al. are favored by the spectrum. We conclude that the EDGES data may be consistent with standard cosmology and astrophysics, without invoking excess radio backgrounds or baryon–dark matter interactions.
影响因子：
7.9
作者：
Draine, B. T.;Miralda-Escude, Jordi
通讯作者：
Miralda-Escude, Jordi