Simulations for single-dish intensity mapping experiments
Simulations for single-dish intensity mapping experiments
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DOI：
10.1093/mnras/stv2153
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发表时间：
2015-07
影响因子：
4.8
通讯作者：
M. Bigot-Sazy;C. Dickinson;R. Battye;I. Browne;Y.-Z. Ma;Y.-Z. Ma;B. Maffei;F. Noviello;M. Remazeilles;P. Wilkinson
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文献类型：
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作者：
M. Bigot-Sazy;C. Dickinson;R. Battye;I. Browne;Y.-Z. Ma;Y.-Z. Ma;B. Maffei;F. Noviello;M. Remazeilles;P. Wilkinson
H I强度映射是一种新兴的探测暗能量的工具。红移的H I信号的观测将受到仪器噪声、大气和银河前景的污染。预计后者比我们希望探测的H I发射亮四个数量级。我们提出了一个模拟的单碟观测，包括1/f和白色噪声的仪器噪声模型，和天空发射与弥漫银河前景和H I发射。我们考虑两种前景清理方法：光谱参数拟合和主成分分析。对于前景和仪器效应的平滑频谱，我们发现参数拟合方法提供的残差仍然受到前景和1/f噪声的污染，但主成分分析可以将这种污染降低到热噪声水平。该方法对于一系列不同的前景和噪声模型是鲁棒的，并且因此构成了从数据恢复H I信号的有前途的方式。然而，它会导致宇宙学信号泄漏到约5%的减去前景中。分量分离方法的效率在很大程度上取决于前景频谱和1/f噪声的平滑度。我们发现，只要在频带上的光谱变化与通道宽度相比是缓慢的，前景清理方法仍然有效。
H I intensity mapping is an emerging tool to probe dark energy. Observations of the redshifted H I signal will be contaminated by instrumental noise, atmospheric and Galactic foregrounds. The latter is expected to be four orders of magnitude brighter than the H I emission we wish to detect. We present a simulation of single-dish observations including an instrumental noise model with 1/f and white noise, and sky emission with a diffuse Galactic foreground and H I emission. We consider two foreground cleaning methods: spectral parametric fitting and principal component analysis. For a smooth frequency spectrum of the foreground and instrumental effects, we find that the parametric fitting method provides residuals that are still contaminated by foreground and 1/f noise, but the principal component analysis can remove this contamination down to the thermal noise level. This method is robust for a range of different models of foreground and noise, and so constitutes a promising way to recover the H I signal from the data. However, it induces a leakage of the cosmological signal into the subtracted foreground of around 5 per cent. The efficiency of the component separation methods depends heavily on the smoothness of the frequency spectrum of the foreground and the 1/f noise. We find that as long as the spectral variations over the band are slow compared to the channel width, the foreground cleaning method still works.