Optical modeling and polarization calibration for CMB measurements with ACTPol and Advanced ACTPol
Optical modeling and polarization calibration for CMB measurements with ACTPol and Advanced ACTPol
复制标题
使用 ACTPol 和 Advanced ACTPol 进行 CMB 测量的光学建模和偏振校准
DOI：
10.1117/12.2231912
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Edward J. Wollack
中科院分区：
文献类型：
--
作者：
B. Koopman;J. Austermann;Hsiao;K. Coughlin;S. Duff;P. Gallardo;M. Hasselfield;S. Henderson;S. Ho;J. Hubmayr;K. Irwin;Dale Li;J. McMahon;F. Nati;M. Niemack;L. Newburgh;L. Page;M. Salatino;A. Schillaci;B. Schmitt;S. Simon;E. Vavagiakis;J. Ward;Edward J. Wollack
阿塔卡马宇宙学望远镜偏振计（ACTPol）是阿塔卡马宇宙学望远镜的偏振敏感升级，位于智利Cerro Toco海拔5190米处。ACTPol使用过渡边缘传感器测辐射热计耦合到正交模换能器来测量宇宙微波背景（CMB）的温度和偏振。探测器角度的校准是产生CMB偏振图的关键步骤。探测器校准中的偏振角偏移会导致从E到B模式的偏振泄漏，并在EB和TB互相关中引起伪信号，这消除了我们测量EB和TB信号的潜在宇宙学源（如宇宙双折射）的能力。我们校准的ACTPol探测器的角度通过整个光学链的射线跟踪设计的探测器的角度，以确定每个探测器的角度在天空中的投影。校准的检测器偏振角的分布与当与EB调零偏移角（将EB互相关功率谱调零所需的角）相比时从零开始的全局偏移角一致。我们提出了光学建模过程。探测器的角度可以通过观测已知的偏振源进行交叉检查，无论这是一个银河系源或实验室参考标准。为了交叉检查ACTPol探测器的角度，我们在望远镜的接收器前面，在接收器和次级反射器之间放置了一个薄膜偏振栅格。利用快速旋转的半波片（HWP）支架，我们以恒定的速度旋转偏振网格，偏振和旋转入射的大气信号。所得到的正弦信号用于确定检测器角度。与第一个ACTPol结果中的EB调零相比，光学建模校准显示出与零全局偏移角一致，并且将继续成为我们校准实施的一部分。先进ACTPol的第一个探测器阵列，ACTPol的下一代升级，将于2016年部署。我们计划继续使用这两种技术，并将它们与高级ACTPol偏振校准的天体物理源测量进行比较。
The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive upgrade to the Atacama Cosmology Telescope, located at an elevation of 5190 m on Cerro Toco in Chile. ACTPol uses transition edge sensor bolometers coupled to orthomode transducers to measure both the temperature and polarization of the Cosmic Microwave Background (CMB). Calibration of the detector angles is a critical step in producing polarization maps of the CMB. Polarization angle offsets in the detector calibration can cause leakage in polarization from E to B modes and induce a spurious signal in the EB and TB cross correlations, which eliminates our ability to measure potential cosmological sources of EB and TB signals, such as cosmic birefringence. We calibrate the ACTPol detector angles by ray tracing the designed detector angle through the entire optical chain to determine the projection of each detector angle on the sky. The distribution of calibrated detector polarization angles are consistent with a global offset angle from zero when compared to the EB-nulling offset angle, the angle required to null the EB cross-correlation power spectrum. We present the optical modeling process. The detector angles can be cross checked through observations of known polarized sources, whether this be a galactic source or a laboratory reference standard. To cross check the ACTPol detector angles, we use a thin film polarization grid placed in front of the receiver of the telescope, between the receiver and the secondary reflector. Making use of a rapidly rotating half-wave plate (HWP) mount we spin the polarizing grid at a constant speed, polarizing and rotating the incoming atmospheric signal. The resulting sinusoidal signal is used to determine the detector angles. The optical modeling calibration was shown to be consistent with a global offset angle of zero when compared to EB nulling in the first ACTPol results and will continue to be a part of our calibration implementation. The first array of detectors for Advanced ACTPol, the next generation upgrade to ACTPol, will be deployed in 2016. We plan to continue using both techniques and compare them to astrophysical source measurements for the Advanced ACTPol polarization calibration.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.