Revisiting constraints on (pseudo)conformal Universe with Planck data

Understand

We revisit constraints on the (pseudo)conformal Universe from the non-observation of statistical anisotropy in the Planck data.

• The quadratic maximal likelihood estimator is applied to the Planck temperature maps at frequencies 143 GHz and 217 GHz as well as their cross-correlation.
• The strongest constraint is obtained in the scenario of the (pseudo)conformal Universe with a long intermediate evolution after conformal symmetry breaking.
• In terms of the relevant parameter (coupling constant), the limit is h^2 <0.0013 at 95% C.L.