Evolution of CMB spectral distortion anisotropies and tests of primordial non-Gaussianity

Abstract

Anisotropies in distortions to the frequency spectrum of the cosmic microwave background (CMB) can be created through spatially varying heating processes in the early Universe. For instance, the dissipation of small-scale acoustic modes does create distortion anisotropies, in particular for non-Gaussian primordial perturbations. In this work, we derive approximations that allow describing the associated distortion field. We provide a systematic formulation of the problem using Fourier-space window functions, clarifying and generalizing previous approximations. Our expressions highlight the fact that the amplitudes of the spectral-distortion fluctuations induced by non-Gaussianity depend also on the homogeneous value of those distortions. Absolute measurements are thus required to obtain model-independent distortion constraints on primordial non-Gaussianity. We also include a simple description for the evolution of distortions through photon diffusion, showing that these corrections can usually be neglected. Our formulation provides a systematic framework for computing higher order correlation functions of distortions with CMB temperature anisotropies and can be extended to describe correlations with polarization anisotropies.

11 pages, 3 figures, accepted by MNRAS

References in corpus (8)

• Probing the scale dependence of non-Gaussianity with spectral distortions of the cosmic microwave background
• Testing the Running of non-Gaussianity through the CMB mu-distortion and the Halo Bias
• Spectral distortions from the dissipation of tensor perturbations
• Angular dependence of primordial trispectra and CMB spectral distortions
• Cosmological constraints from $\mu E$ cross-correlations
• Anisotropic CMB distortions from non-Gaussian isocurvature perturbations
• Probing early-universe phase transitions with CMB spectral distortions
• Probing small-scale non-Gaussianity from anisotropies in acoustic reheating

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• Primordial non-Gaussianity with $\mu$-type and $y$-type spectral distortions: exploiting Cosmic Microwave Background polarization and dealing with secondary sources
• Non-Gaussianity constraints from Planck spectral distortion cross-correlations
• CMB $\mu T$ cross-correlations as a probe of PBH scenarios
• Spectral Distortion Anisotropy from Inflation for Primordial Black Holes
• Primordial tensor bispectra in $\mu$-CMB cross-correlations
• Leverage on small-scale primordial non-Gaussianity through cross-correlations between CMB $E$-mode and $\mu$-distortion anisotropies
• Primordial magnetic non-Gaussianity with generic vacua and detection prospects in CMB spectral distortions