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arXiv 0908.1840astro-ph.CO
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CMBR弱透镜和HI 21 cm互相关角功率谱

CMBR Weak Lensing and HI 21-cm Cross-correlation Angular Power Spectrum

Tapomoy Guha Sarkar

摘要:

CMBR的弱引力透镜在温度图上表现为次级各向异性。通过剪切场和会聚场量化的这种效应,影响了宇宙的基本大尺度结构、几何形状和演化历史。因此,它被认为是宇宙学的一个重要观测探测器。CMBR温度图的去透镜化对于探测引力波产生的B模也是至关重要的。未来的观测红移21厘米辐射的宇宙中性氢(HI)的分布举行的潜力,探测LSS在一个大的红移范围。我们研究了再电离后HI信号与弱透镜会聚场的相关性。假设HI服从暗物质分布,多极\ell的互相关角功率谱与冷暗物质功率谱成正比,功率谱的计算公式为\ell /r,其中r表示HI所在位置与红移的共动距离.交叉相关的幅度取决于特定的HI分布,扰动的增长和基本的宇宙学模型的数量。在理想情况下,我们发现互相关信号的统计显著检测是可能的。如果检测到,互相关信号持有的宇宙学参数的联合估计的可能性,也测试各种CMBR去透镜估计。

英文摘要:

Weak gravitational lensing of the CMBR manifests as a secondary anisotropy in the temperature maps. The effect, quantified through the shear and convergence fields imprint the underlying large scale structure (LSS), geometry and evolution history of the Universe. It is hence perceived to be an important observational probe of cosmology. De-lensing the CMBR temperature maps is also crucial for detecting the gravitational wave generated B-modes. Future observations of redshifted 21-cm radiation from the cosmological neutral hydrogen (HI) distribution hold the potential of probing the LSS over a large redshift range. We have investigated the correlation between post-reionization HI signal and weak lensing convergence field. Assuming that the HI follows the dark matter distribution, the cross-correlation angular power spectrum at a multipole \ell is found to be proportional to the cold dark matter power spectrum evaluated at \ell/r, where r denotes the comoving distance to the redshift where the HI is located. The amplitude of the ross-correlation depends on quantities specific to the HI distribution, growth of perturbations and also the underlying cosmological model. In an ideal ituation, we found that a statistically significant detection of the cross-correlation signal is possible. If detected, the cross-correlation signal hold the possibility of a joint estimation of cosmological parameters and also test various CMBR de-lensing estimators.

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