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arXiv 1702.03317astro-ph.CO
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玻恩近似下的CMB弱透镜:数值方法

CMB weak-lensing beyond the Born approximation: a numerical approach

Giulio Fabbian, Matteo Calabrese, Carmelita Carbone

摘要:

我们进行了一个完整的研究引力透镜效应超越玻恩近似的宇宙微波背景(CMB)各向异性使用多透镜射线追踪技术,通过宇宙学N体模拟的DEMNUNI套件。解释大尺度结构的非线性演化的二阶效应的影响被评估为第一次传播完整的CMB透镜雅可比矩阵连同光线轨迹。我们仔细研究了我们的方法对光线跟踪过程中的几个数值效应和N体模拟本身的鲁棒性,并没有发现大的污染的证据。我们讨论了超越玻恩校正对透镜CMB观测量的影响,并将我们的结果与最近出现在文献中的分析预测进行了比较,发现了很好的一致性,并将这些结果扩展到更小的角尺度。我们测量的引力引起的CMB偏振旋转出现在第二阶,并比较这一结果与最新的分析预测。最后展望了未来CMB-S4实验对超玻恩效应的探测前景。我们表明,只有在实现了对河外前景的良好控制的情况下,才能测量温度功率谱的修正。相反,E模和B模功率谱的超越玻恩修正将更难检测。

英文摘要:

We perform a complete study of the gravitational lensing effect beyond the Born approximation on the Cosmic Microwave Background (CMB) anisotropies using a multiple-lens raytracing technique through cosmological N-body simulations of the DEMNUni suite. The impact of second order effects accounting for the non-linear evolution of large-scale structures is evaluated propagating for the first time the full CMB lensing jacobian together with the light rays trajectory. We carefully investigate the robustness of our approach against several numerical effects in the raytracing procedure and in the N-body simulation itself, and find no evidence of large contaminations. We discuss the impact of beyond-Born corrections on lensed CMB observables, and compare our results with recent analytical predictions that appeared in the literature, finding a good agreement, and extend these results to smaller angular scales. We measure the gravitationally-induced CMB polarization rotation that appears at second order, and compare this result with the latest analytical predictions. We then present the detection prospect of beyond-Born effects with the future CMB-S4 experiment. We show that corrections to the temperature power spectrum can be measured only if a good control of the extragalactic foregrounds is achieved. Conversely, the beyond-Born corrections on E and B-modes power spectra will be much more difficult to detect.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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