Abstract. Current and upcoming experimental efforts to unveil the details of the inflationary epoch have primordial non-Gaussianity as one of the main targets. Indeed, detecting a deviation from Gaussianity in the statistics of primordial perturbations would shed light on the interactions between the degrees of freedom active during inflation.
Deviations of the CMB spectrum from a black-body are a powerful probe of the three-point function of curvature perturbations. Dissipation of acoustic waves in the photon- electron-baryon fluid heats the plasma: the heating is not balanced by an appropriate change in photon number, and a Bose-Einstein spectrum is formed. A non-zero three-point function of curvature perturbations makes the heating rate spatially dependent, so that the observed chemical potential in the sky will be anisotropic and correlated with large-scale temperature fluctuations.
In this talk I discuss how the angular correlation of temperature anisotropies and spectral distortions is insensitive to contamination from late-time projection effects (unlike other observables like the CMB temperature bispectrum), making it an excellent, albeit futuristic, probe of primordial non- Gaussianity.
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