Cosmic Microwave Background Bispectrum from the Lensing--Rees-Sciama Correlation Reexamined: Effects of Non-linear Matter Clustering

Abstract

The bispectrum of the cosmic microwave background (CMB) generated by a correlation between a time-dependent gravitational potential and the weak gravitational lensing effect provides a direct measurement of the influence of dark energy on CMB. This bispectrum is also known to yield the most important contamination of the so-called "local-form" primordial bispectrum, which can be used to rule out all single-field inflation models. In this paper, we reexamine the effect of non-linear matter clustering on this bispectrum. We compare three different approaches: the 3rd-order perturbation theory (3PT), and two empirical fitting formulae available in the literature, finding that detailed modeling of non-linearity appears to be not very important, as most of the signal-to-noise comes from the squeezed triangle, for which the correlation in the linear regime dominates. The expected signal-to-noise ratio for an experiment dominated by the cosmic variance up to $l_{\max }=1500$ is about 5, which is much smaller than the previous estimates including non-linearity, but agrees with the estimates based on the linear calculation. We find that the difference between the linear and non-linear predictions is undetectable, and does not alter the contamination of the local-form primordial non-Gaussianity.

9 pages, 7 figures; Submitted to PRD. The unlensed Cl in the lensing-ISW bispectrum has been replaced by the lensed Cl following arXiv:1101.2234

References in corpus (3)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Impact of Secondary non-Gaussianities on the Search for Primordial Non-Gaussianity with CMB Maps
• Cosmic Microwave Background--Weak Lensing Correlation: Analytical and Numerical Study of Non-linearity and Implications for Dark Energy

Cited by in corpus (8)

• Planck 2013 Results. XXIV. Constraints on primordial non-Gaussianity
• Primordial black holes as a tool for constraining non-Gaussianity
• Integrated Sachs Wolfe Effect and Rees Sciama Effect
• Foreground Biases on Primordial Non-Gaussianity Measurements from the CMB Temperature Bispectrum: Implications for Planck and Beyond
• Polarization bispectrum for measuring primordial magnetic fields
• Optimal bispectrum estimator and simulations of the the CMB Lensing-ISW non-Gaussian signal
• Future CMB ISW-Lensing bispectrum constraints on modified gravity in the Parameterized Post-Friedmann formalism
• Removing the ISW-lensing bias from the local-form primordial non-Gaussianity estimation