Optimal limits on primordial magnetic fields from CMB temperature bispectrum of passive modes
Optimal limits on primordial magnetic fields from CMB temperature bispectrum of passive modes
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DOI：
10.1088/1475-7516/2012/03/041
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发表时间：
2012-01
影响因子：
6.4
通讯作者：
M. Shiraishi;Daisuke Nitta;Shuichiro Yokoyama;K. Ichiki
中科院分区：
文献类型：
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作者：
M. Shiraishi;Daisuke Nitta;Shuichiro Yokoyama;K. Ichiki
本文研究了宇宙微波背景（CMB）各向异性应力的标量分量和张量分量的自相关双谱和交叉相关双谱诱导的强度（温度）模式的原始磁场（PMF）强度的边界。首先，我们构造了由任意扰动组成的PMFs的微波辐射强度和偏振双谱的一般公式。为了减少对大量多极位形的计算时间，我们推导了一个精确跟踪CMB双谱形状的近似表达式，并证明了来自pmf的非高斯结构被归类为局部型位形。根据仪器噪声和分辨率的信息，根据近似公式计算信噪比，我们发现，当磁谱接近尺度不变（nB = - 2.9）时，磁场强度的期望上界在WMAP和PLANCK实验中以95%置信水平在1Mpc尺度上平滑，分别为B1Mpc < 4.0 ~ 6.7nG和3.8 ~ 6.5nG，这取决于磁场产生的能量尺度从1014GeV到103GeV。我们的新结果意味着先前粗略的讨论略微高估了。
We investigate bounds on the strength of the primordial magnetic field (PMF) from the cosmic microwave background (CMB) bispectra of the intensity (temperature) modes induced from the auto- and cross-correlated bispectra of the scalar and tensor components of the PMF anisotropic stress. At first, we construct a general formula for the CMB intensity and polarization bispectra from PMFs composed of any type of perturbation. Then we derive an approximate expression which traces the exact shape of the CMB bispectrum in order to reduce the computation time with respect to a large number of the multipole configurations, and also show that the non-Gaussian structure coming from PMFs is classified as the local-type configuration. Computing the signal-to-noise ratio on the basis of the approximate formula with the information of the instrumental noises and resolutions, we find expected upper bounds on the magnetic field strength, when the magnetic spectrum is nearly scale invariant (nB = −2.9), smoothed on 1Mpc scale at 95% confidence level from the WMAP and PLANCK experiments as B1Mpc < 4.0−6.7nG and 3.8−6.5nG, respectively, depending on the energy scale of the magnetic field production from 1014GeV to 103GeV. Our new consequences imply slight overestimations by the previous rough discussions.