Non-Gaussianities from Perturbing Recombination

Abstract

We approximately compute the bispectrum induced on the CMB temperature by fluctuations in the standard recombination epoch. Of all the second order sources that can induce non-Gaussianity during recombination, we concentrate on those proportional to the perturbation in the free electron density, which is about a factor of 5 larger than the other first order perturbations. This term induces some non-Gaussianity by delaying the time of recombination and by changing the photon diffusion scale. We find that the signal is not scale invariant, peaked on squeezed triangles with the smaller multipole around the scale of the first acoustic peak, and that its size corresponds to an effective f_NL ~ -3.5, which could be marginally detected by Planck if both temperature and polarization are measured.

37 pages, 13 figures. v2: Corrected algebraic mistake, numerical results marginally affected; added references

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Cited by in corpus (33)

• Planck 2013 Results. XXIV. Constraints on primordial non-Gaussianity
• Non-Gaussianities in Single Field Inflation and their Optimal Limits from the WMAP 5-year Data
• Hunting for Primordial Non-Gaussianity in the Cosmic Microwave Background
• CMB at 2x2 order: the dissipation of primordial acoustic waves and the observable part of the associated energy release
• Primordial non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure
• The cosmic microwave background bispectrum from the non-linear evolution of the cosmological perturbations
• The CMB bispectrum in the squeezed limit
• The intrinsic bispectrum of the Cosmic Microwave Background [PhD thesis]
• Compensated Isocurvature Perturbations and the Cosmic Microwave Background
• The CMB bispectrum from recombination
• Non-Gaussianity and the CMB Bispectrum: confusion between Primordial and Lensing-Rees Sciama contribution?
• Analytic formulae of the CMB bispectra generated from non-Gaussianity in the tensor and vector perturbations
• Mass function and bias of dark matter halos for non-Gaussian initial conditions
• The EFT Likelihood for Large-Scale Structure
• The intrinsic B-mode polarisation of the Cosmic Microwave Background
• Impact of polarisation on the intrinsic CMB bispectrum
• The Cosmological OTOC: Formulating new cosmological micro-canonical correlation functions for random chaotic fluctuations in Out-of-Equilibrium Quantum Statistical Field Theory
• The full CMB temperature bispectrum from single-field inflation
• Perturbed Recombination from Dark Matter Annihilation
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• A new line-of-sight approach to the non-linear Cosmic Microwave Background
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• Non-Gaussian CMB and LSS statistics beyond polyspectra
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• Unified approach to secondary effects on the CMB B-mode polarization
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• O-V-S-Z and friends: Non-Gaussianity from inhomogeneous reionization
• Probing small-scale baryon and dark matter isocurvature perturbations with cosmic microwave background anisotropies