Gravitational lensing of the cosmic microwave background by nonlinear structures

Abstract

Weak gravitational lensing changes the angular power spectra of the cosmic microwave background (CMB) temperature and polarization in a characteristic way containing valuable information for cosmological parameter estimation and weak lensing reconstructions. So far, analytical expressions for the lensed CMB power spectra assume the probability density function (PDF) of the lensing excursion angle to be Gaussian. However, coherent light deflection by nonlinear structures at low redshifts causes deviations from a pure Gaussian PDF. Working in the flat-sky limit we develop a method for computing the lensed CMB power spectra which takes these non-Gaussian features into account. Our method does not assume any specific PDF but uses instead an expansion of the characteristic function of the lensing excursion angle into its moments. Measuring these in the CMB lensing deflection field obtained from the Millennium Simulation we show that the change in the lensed power spectra is only at the 0.1% - 0.4% level on very small scales (below 4 arcmin) and demonstrate that the assumption of a Gaussian lensing excursion angle PDF is well applicable.

9 pages, 2 figures, submitted to MNRAS

References in corpus (8)

• Weak Gravitational Lensing of the CMB
• The large-scale structure of the Universe
• Detection of Gravitational Lensing in the Cosmic Microwave Background
• Probing cosmological parameters with the CMB: Forecasts from full Monte Carlo simulations
• Correlation of CMB with large-scale structure: II. Weak lensing
• CMB Lensing Constraints on Neutrinos and Dark Energy
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• Lensed CMB temperature and polarization maps from the Millennium Simulation

Cited by in corpus (7)

• CMB lensing reconstruction biases in cross-correlation with large-scale structure probes
• Lensing Reconstruction in Post-Born Cosmic Microwave Background Weak Lensing
• High precision simulations of weak lensing effect on Cosmic Microwave Background polarization
• Weak gravitational lensing of intrinsically aligned galaxies
• Born-corrections to weak lensing of the cosmic microwave background temperature and polarisation anisotropies
• Evolution of intrinsic ellipticity correlations due to peculiar motion
• Extreme value statistics of CMB lensing deflection angles