Forecast of CMB TB and EB correlations for AliCPT-1

Understand

The correlations between T, E modes and B modes in cosmic microwave background (CMB) radiation, which are expected to vanish under parity symmetry, have become a sensitive probe of the new physics beyond the standard model.

• In this paper, we forecast the estimation of TB and EB cross power spectra using NILC and cILC on AliCPT-1 simulations together with Planck HFI and WMAP K maps as ancillary data.
• We find that, NILC performs better than cILC on measuring TB and EB correlations in light of its lower uncertainties.
• In terms of the birefringence angle estimation without assuming systematic errors, the combination of CMB TB and EB spectra from NILC cleaned simulations could reach a sensitivity of $|\beta|<0.058^\circ$ with 2$\sigma$ significance for the first observing season of AliCPT.