POLARBEAR constraints on cosmic birefringence and primordial magnetic fields
POLARBEAR constraints on cosmic birefringence and primordial magnetic fields
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DOI：
10.1103/physrevd.92.123509
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发表时间：
2015-12-08
影响因子：
5
通讯作者：
Zahn, Oliver
中科院分区：
文献类型：
--
作者：
Ade, Peter A. R.;Arnold, Kam;Zahn, Oliver
本文利用偏振背景辐射实验（POLARBEAR）第一季观测中宇宙微波背景测量的偶宇称e模和奇宇称b模偏振的四点相关，约束了各向异性宇宙双折射。我们发现来自任何违反宇称过程的各向异性宇宙双折射信号都与零一致。由各向异性宇宙双折射产生的法拉第旋转可以与原始磁场产生的等效量进行比较。包含系统不确定性的等效原始磁场振幅的95%置信水平（C.L.）上限为93纳高斯（nG）。这个法拉第旋转的四点相关约束比2015年普朗克测量的b模式两点相关约束法拉第旋转的贡献推断出的1380 nG的上限严格约15倍。原始磁场产生的度量扰动也会影响b模功率谱。利用POLARBEAR测量的b模功率谱（两点相关），我们在假设场振幅平坦的原始磁场上设置了95% C.L.上限3.9 nG。这一极限与普朗克2015在温度和极化的两点相关分析中发现的结果相当。我们进行了一套系统误差测试，没有发现污染的证据。这项工作标志着各向异性宇宙双折射或原始磁场首次被限制在亚度尺度上。
We constrain anisotropic cosmic birefringence using four-point correlations of even-parity E-mode and odd-parity B-mode polarization in the cosmic microwave background measurements made by the POLARization of the Background Radiation (POLARBEAR) experiment in its first season of observations. We find that the anisotropic cosmic birefringence signal from any parity-violating processes is consistent with zero. The Faraday rotation from anisotropic cosmic birefringence can be compared with the equivalent quantity generated by primordial magnetic fields if they existed. The POLARBEAR non-detection translates into a 95% confidence level (C.L.) upper limit of 93 nanogauss (nG) on the amplitude of an equivalent primordial magnetic field inclusive of systematic uncertainties. This four-point correlation constraint on Faraday rotation is about 15 times tighter than the upper limit of 1380 nG inferred from constraining the contribution of Faraday rotation to two-point correlations of B-modes measured by Planck in 2015. Metric perturbations sourced by primordial magnetic fields would also contribute to the B-mode power spectrum. Using the POLARBEAR measurements of the B-mode power spectrum (two-point correlation), we set a 95% C.L. upper limit of 3.9 nG on primordial magnetic fields assuming a flat prior on the field amplitude. This limit is comparable to what was found in the Planck 2015 two-point correlation analysis with both temperature and polarization. We perform a set of systematic error tests and find no evidence for contamination. This work marks the first time that anisotropic cosmic birefringence or primordial magnetic fields have been constrained from the ground at subdegree scales.