Parity violation of primordial magnetic fields in the CMB bispectrum
Parity violation of primordial magnetic fields in the CMB bispectrum
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DOI：
10.1088/1475-7516/2012/06/015
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发表时间：
2012-02
影响因子：
6.4
通讯作者：
M. Shiraishi
中科院分区：
文献类型：
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作者：
M. Shiraishi
研究了原初磁场诱导的宇宙微波背景双谱宇称破缺现象。导出了非螺旋和螺旋保偏光纤产生的CMB双谱的一般公式，发现螺旋保偏光纤产生的特征信号在宇称守恒的情况下消失，如强度-强度-强度双谱由∑ 3 n = 1 ln = odd产生.为了快速数值计算CMB双谱，我们利用极点近似将单圈公式简化为树级公式。然后，我们表明，磁各向异性应力，这取决于非螺旋和螺旋保偏光纤的平方，并作为源的CMB波动，产生本地型非高斯。将标量模和张量模组成的CMB双谱与噪声谱进行比较，发现假设从大统一能量标度（1014 GeV）到电弱能量标度（103 GeV）产生近似标度不变的非螺旋和螺旋保偏光纤，在B1 Mpc; 2/3 × 1Mpc; 1/3 > 2.7−4.5nG，其中B1 Mpc;和B11 Mpc;分别是在1 Mpc上平滑的非螺旋和螺旋PMF强度。
We study the parity violation in the cosmic microwave background (CMB) bispectrum induced by primordial magnetic fields (PMFs). Deriving a general formula for the CMB bispectrum generated from not only non-helical but also helical PMFs, we find that helical PMFs produce characteristic signals, which disappear in parity-conserving cases, such as the intensity-intensity-intensity bispectra arising from ∑3n=1ln = odd. For fast numerical calculation of the CMB bispectrum, we reduce the one-loop formula to the tree-level one by using the so-called pole approximation. Then, we show that the magnetic anisotropic stress, which depends quadratically on non-helical and helical PMFs and acts as a source of the CMB fluctuation, produces the local-type non-Gaussianity. Comparing the CMB bispectra composed of the scalar and tensor modes with the noise spectra, we find that assuming the generation of the nearly scale-invariant non-helical and helical PMFs from the grand unification energy scale (1014GeV) to the electroweak one (103GeV), the intensity-intensity-intensity bispectrum for ∑3n=1ln = odd can be observed by the WMAP experiment under the condition that B1Mpc;2/3ℬ1Mpc;1/3 > 2.7−4.5nG with B1Mpc; and ℬ1Mpc; being the non-helical and helical PMF strengths smoothed on 1 Mpc, respectively.