Speaker
Description
Acoustic dampening of the cosmic microwave background (CMB) power spectrum results from imperfect photon-baryon coupling in the pre-recombination plasma. At redshift 5 × 104 < z < 2 × 106 , the plasma has an effective chemical potential, and energy injections from acoustic dampening in this era create μ- type spectral distortions of the CMB. These μ-distortions trace the underlying photon density fluctuations, probing the primordial power spectrum from 50 Mpc−1 < k < 104 Mpc−1 . Small-scale power modulated by long-wavelength modes from squeezed-limit non-Gaussianities introduces cross-correlations between CMB temperature anisotropies and μ-distortions. Under single-field inflation models, μT correlations measured from an observer in an inertial frame should be exactly zero, thus any measured correlation rules out single- field inflation models. We are forecasting how well CMB-S4 + SKA1 & 2 can constrain primordial squeezed- limit non-Gaussianity—parameterized by fNL—using measurements of C μT ` . Using current specifications and foreground modeling, we expect σ(fNL) ∼ 5.
