论文标题

超越Planck X.带通和梁泄漏校正

BeyondPlanck X. Bandpass and beam leakage corrections

论文作者

Svalheim, T. L., Andersen, K. J., Aurlien, R., Banerji, R., Bersanelli, M., Bertocco, S., Brilenkov, M., Carbone, M., Colombo, L. P. L., Eriksen, H. K., Foss, M. K., Franceschet, C., Fuskeland, U., Galeotta, S., Galloway, M., Gerakakis, S., Gjerløw, E., Hensley, B., Herman, D., Iacobellis, M., Ieronymaki, M., Ihle, H. T., Jewell, J. B., Karakci, A., Keihänen, E., Keskitalo, R., Maggio, G., Maino, D., Maris, M., Paradiso, S., Partridge, B., Reinecke, M., Suur-Uski, A. -S., Tavagnacco, D., Thommesen, H., Watts, D. J., Wehus, I. K., Zacchei, A., Zonca, A.

论文摘要

我们讨论了在Planck LFI测量中应用的贝叶斯超越CMB分析管道中带通和梁泄漏校正的处理。作为预备步骤,我们首先对标称LFI带通道的校正进行了三个校正,包括在61 GHz的地面测量设备中删除已知的系统效应;平滑波波涟漪;和边缘正则化。这些修饰的主要净影响是70 GHz带通+0.6 GHz的总体转变;我们认为,对来自普朗克或Planck Beyond Planck的LFI数据产品的任何分析都应使用这些新的带通路。此外,我们适合单个自由带通参数,适用于$δ_i=δ_0 +δ_i$的每个辐射计,其中$δ_0$代表每个频段的绝对频移,$δ_i$是每个检测器的相对移位。绝对校正仅适合30 GHz,基于整个$χ^2 $的可能性,导致校正$δ_{30} = 0.24 \ pm0.03 \,$ ghz。相对校正是使用虚假地图方法拟合的,这与WMAP团队开创的方法根本相似,但没有引入许多额外的自由度。所有带通参数均在主要超越吉布斯链中的标准大都市采样器中进行采样,因此在分析中将带通的不确定性传播到所有其他数据产品。总体而言,我们发现我们的带通模型大大降低了泄漏效应。对于梁泄漏校正,我们采用了官方的Planck LFI梁估计,而无需额外的自由度,并且只能在基础天空模型上边缘化。我们注意到,这是Planck LFI地图首次包括Beam不匹配的泄漏。

We discuss the treatment of bandpass and beam leakage corrections in the Bayesian BeyondPlanck CMB analysis pipeline as applied to the Planck LFI measurements. As a preparatory step, we first apply three corrections to the nominal LFI bandpass profiles including removal of a known systematic effect in the ground measuring equipment at 61 GHz; smoothing of standing wave ripples; and edge regularization. The main net impact of these modifications is an overall shift in the 70 GHz bandpass of +0.6 GHz; we argue that any analysis of LFI data products, either from Planck or BeyondPlanck, should use these new bandpasses. In addition, we fit a single free bandpass parameter for each radiometer of the form $Δ_i = Δ_0 + δ_i$, where $Δ_0$ represents an absolute frequency shift per frequency band and $δ_i$ is a relative shift per detector. The absolute correction is only fitted at 30 GHz with a full $χ^2$-based likelihood, resulting in a correction of $Δ_{30}=0.24\pm0.03\,$GHz. The relative corrections are fitted using a spurious map approach, fundamentally similar to the method pioneered by the WMAP team, but without introducing many additional degrees of freedom. All bandpass parameters are sampled using a standard Metropolis sampler within the main BeyondPlanck Gibbs chain, and bandpass uncertainties are thus propagated to all other data products in the analysis. In total, we find that our bandpass model significantly reduces leakage effects. For beam leakage corrections, we adopt the official Planck LFI beam estimates without additional degrees of freedom, and only marginalize over the underlying sky model. We note that this is the first time leakage from beam mismatch has been included for Planck LFI maps.

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