论文标题

超越普兰克二世。通过Gibbs抽样制作CMB图

BeyondPlanck II. CMB map-making through Gibbs sampling

论文作者

Keihänen, E., Suur-Uski, A. -S., 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., Keskitalo, R., Maggio, G., Maino, D., Maris, M., Mennella, A., Paradiso, S., Partridge, B., Reinecke, M., Svalheim, T. L., Tavagnacco, D., Thommesen, H., Tomasi, M., Watts, D. J., Wehus, I. K., Zacchei, A.

论文摘要

我们为基于现有破坏方法的基于CMB测量的地图制作问题提供了吉布斯采样解决方案。 Gibbs采样将计算沉重的破坏问题分为两个单独的步骤。噪声过滤和映射箱。被认为是两个单独的步骤,两者在计算上比解决合并问题便宜得多。与传统方法相比,这提供了巨大的性能优势,并首次使我们将毁灭性基线长度带入单个样本。我们将Gibbs程序应用于模拟Planck 30 GHz数据。我们发现,通过将模拟噪声填充为Gibbs过程的一部分,可以有效地处理时间序数据中的差距。 Gibbs程序产生了一系列地图样本,我们可以从中计算出最佳估计图的后平均值。链中的变化提供了有关相关残差噪声的信息,而无需构建完整的噪声协方差矩阵。但是,如果仅需要单个最大样品频率映射估计值,我们发现在迭代总数方面,传统的共轭梯度求解器的收敛速度比Gibbs采样器快得多。 Gibbs采样方法的概念优势在于统计明确定义明确的错误传播和系统的误差校正,并且该方法构成了BeyondPlanck框架中采用的映射算法的概念基础,该算法实现了CMB观察的首次端到端端到端贝叶斯分析管道。

We present a Gibbs sampling solution to the map-making problem for CMB measurements, building on existing destriping methodology. Gibbs sampling breaks the computationally heavy destriping problem into two separate steps; noise filtering and map binning. Considered as two separate steps, both are computationally much cheaper than solving the combined problem. This provides a huge performance benefit as compared to traditional methods, and allows us for the first time to bring the destriping baseline length to a single sample. We apply the Gibbs procedure to simulated Planck 30 GHz data. We find that gaps in the time-ordered data are handled efficiently by filling them with simulated noise as part of the Gibbs process. The Gibbs procedure yields a chain of map samples, from which we may compute the posterior mean as a best-estimate map. The variation in the chain provides information on the correlated residual noise, without need to construct a full noise covariance matrix. However, if only a single maximum-likelihood frequency map estimate is required, we find that traditional conjugate gradient solvers converge much faster than a Gibbs sampler in terms of total number of iterations. The conceptual advantages of the Gibbs sampling approach lies in statistically well-defined error propagation and systematic error correction, and this methodology forms the conceptual basis for the map-making algorithm employed in the BeyondPlanck framework, which implements the first end-to-end Bayesian analysis pipeline for CMB observations.

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