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首页> 外文期刊>The Astrophysical Journal. Supplement Series >Fast pixel space convolution for cosmic microwave background surveys with asymmetric beams and complex scan strategies: FEBeCoP
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Fast pixel space convolution for cosmic microwave background surveys with asymmetric beams and complex scan strategies: FEBeCoP

机译：具有不对称光束和复杂扫描策略的宇宙微波背景调查的快速像素空间卷积：FEBeCoP

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摘要

Precise measurement of the angular power spectrum of the cosmic microwave background (CMB) temperature and polarization anisotropy can tightly constrain many cosmological models and parameters. However, accurate measurements can only be realized in practice provided all major systematic effects have been taken into account. Beam asymmetry, coupled with the scan strategy, is a major source of systematic error in scanning CMB experiments such as Planck, the focus of our current interest. We envision Monte Carlo methods to rigorously study and account for the systematic effect of beams in CMB analysis. Toward that goal, we have developed a fast pixel space convolution method that can simulate sky maps observed by a scanning instrument, taking into account real beam shapes and scan strategy. The essence is to pre-compute the "effective beams" using a computer code, "Fast Effective Beam Convolution in Pixel space" (FEBeCoP), that we have developed for the Planck mission. The code computes effective beams given the focal plane beam characteristics of the Planck instrument and the full history of actual satellite pointing, and performs very fast convolution of sky signals using the effective beams. In this paper, we describe the algorithm and the computational scheme that has been implemented. We also outline a few applications of the effective beams in the precision analysis of Planck data, for characterizing the CMB anisotropy and for detecting and measuring properties of point sources.
机译：精确测量宇宙微波背景（CMB）温度的角功率谱和极化各向异性可以严格限制许多宇宙学模型和参数。但是，只有在考虑了所有主要系统影响的情况下，才能在实践中实现准确的测量。光束不对称性加上扫描策略是扫描CMB实验（例如普朗克）（我们目前关注的焦点）中系统误差的主要来源。我们设想了蒙特卡洛方法来严格研究和说明梁在CMB分析中的系统作用。为了实现这一目标，我们开发了一种快速像素空间卷积方法，该方法可以模拟扫描仪观察到的天空图，同时考虑到实际的光束形状和扫描策略。本质是使用我们为普朗克任务开发的计算机代码“像素空间中的快速有效光束卷积”（FEBeCoP）预计算“有效光束”。该代码根据普朗克仪器的焦平面波束特性和实际卫星指向的全部历史来计算有效波束，并使用有效波束对天空信号进行非常快速的卷积。在本文中，我们描述了已经实现的算法和计算方案。我们还将概述有效光束在Planck数据精度分析，表征CMB各向异性以及检测和测量点源特性方面的一些应用。

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