Speaker
Description
The dissipation of primordial perturbation modes with wavenumbers $50\,{\rm Mpc}^{-1} < k < 10^4 \,{\rm Mpc}^{-1}$ in the early Universe cause $\mu$-type spectral distortions to the average CMB blackbody radiation. Besides, some inflation scenarios (multi-field or single-field inflation with modified initial state) predict large primordial non-Gaussianity at these scales, so that non-Gaussian couplings between short and long-wavelength modes can modulate the damping of small-scale perturbations across different directions in the sky, and thus induce anisotropic $\mu$-distortions which are furthermore correlated with CMB temperature and polarization anisotropies.
Through signal enhancement by cross-correlation with CMB anisotropies, the $\mu$-distortion anisotropies could potentially be detected by future CMB imagers like the LiteBIRD satellite, and would allow to constrain $f_{\rm NL}$ at the very small scales $50\,{\rm Mpc}^{-1} < k < 10^4 \,{\rm Mpc}^{-1}$ which are inaccessible to both CMB anisotropies and LSS surveys.
In this talk we will present our forecasts on the recovery of the cross-power spectra $C_\ell^{\mu T}$ and $C_\ell^{\mu E}$ between $\mu$-distortion anisotropies and CMB temperature and $E$-mode polarization anisotropies in the presence of astrophysical foregrounds for a LiteBIRD-type experiment. In particular, we will show how $\mu$-$E$ correlations (i.e. $C_\ell^{\mu E}$) actually provide more constraining power on $f_{\rm NL}$ than $\mu$-$T$ correlations in the presence of foregrounds, and how the sensitivity to $f_{\rm NL}$ at small scales can be further increased by the joint analysis of $\mu$-$T$ and $\mu$-$E$ correlations.
