NonGaussianity constraints with anisotropic μ distortion measurements from Planck
Abstract
Primordial nonGaussianity can source μdistortion anisotropies that are correlated with the largescale temperature and polarization signals of the cosmic microwave background (CMB). A measurement of μT and μE correlations can therefore be used to constrain it on wavelengths of perturbations not directly probed by the standard CMB anisotropies. We carry out a first rigorous search for μdistortion anisotropies with Planck data, applying the welltested constrained ILC componentseparation method combined with the needlet framework. We correlate the reconstructed μ map with the CMB anisotropies to derive constraints on the amplitude f_{NL} of the local form bispectrum, specifically on the squeezed configurations with effective wavenumbers $k_s \simeq {740}\, \mathrm{Mpc^{1}}$ and $k_L \simeq {0.05}\, \mathrm{Mpc^{1}}$, improving previously estimated constraints by more than an order of magnitude. This enhancement is owing to the fact that we are able to use the full multipole information by carefully controlling biases and systematic effects in the analysis. We also for the first time incorporate constraints from measurements of μE correlations, which further tighten the limits. A combination of the derived Planck μT and μE power spectra yields f_{NL} ≲ 6800 (95 per cent c.l.) on this highly squeezed bispectrum. This is only ≃3 times weaker than the anticipated constraint from Litebird. Furthermore we show that a combination of Litebird with Planck can improve the expected future constraint by ${\simeq}20{{\%}}$. These limits can be used to constrain multifield inflation models and primordial black hole formation scenarios, thus providing a promising novel avenue forward in CMB cosmology.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 October 2022
 DOI:
 10.1093/mnras/stac2082
 arXiv:
 arXiv:2205.15971
 Bibcode:
 2022MNRAS.515.5847R
 Keywords:

 cosmology;
 cosmic background radiation;
 early Universe;
 inflation;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 Comments welcome. Submitted to MNRAS