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arXiv 0903.2806astro-ph.CO
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暴胀过程中非对易几何的CMB约束

CMB constraints on noncommutative geometry during inflation

Khamphee Karwan

摘要:

在暴胀初期时空是非对易的假设下,我们研究了密度扰动的原初功率谱。由于时空的非对易性,原初功率谱可能失去旋转不变性。利用k-暴胀模型和慢滚近似,我们证明了原初功率谱对转动不变性的偏离依赖于非对易长度尺度L_s的大小,而不依赖于声速。我们约束的贡献,从时空的非对易性的协方差矩阵的谐波系数的CMB各向异性使用五年WMAP CMB地图。我们发现L_s的上界依赖于声速和慢滚参数的乘积。用WMAP五年观测结果的宇宙学参数估计该乘积,在99.7%置信水平下,L_s的上界小于10^{-27} cm。

英文摘要:

We investigate the primordial power spectrum of the density perturbations based on the assumption that spacetime is noncommutative in the early stage of inflation. Due to the spacetime noncommutativity, the primordial power spectrum can lose rotational invariance. Using the k-inflation model and slow-roll approximation, we show that the deviation from rotational invariance of the primordial power spectrum depends on the size of noncommutative length scale L_s but not on sound speed. We constrain the contributions from the spacetime noncommutativity to the covariance matrix for the harmonic coefficients of the CMB anisotropies using five-year WMAP CMB maps. We find that the upper bound for L_s depends on the product of sound speed and slow-roll parameter. Estimating this product using cosmological parameters from the five-year WMAP results, the upper bound for L_s is estimated to be less than 10^{-27} cm at 99.7% confidence level.

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