Testing CPT symmetry with CMB measurements

Aims. We study the possibility of testing Charge-Parity-Time Reversal symmetry (CPT) with cosmic microwave background (CMB) measurements. Methods. Working with an effective lagrangian of the photon with CPT violation L similar to p(mu)A(nu)(F) over tilde (mu nu), which causes the polarization vectors of the propagating CMB photons to be rotated, we determine the rotation angle. a using the BOOMERanG 2003 and the WMAP3 angular power spectra. Results. In this analysis, we have included the newly-released TC and GC (l < 450) information of WMAP3 and found Delta alpha = - 6.2 +/- 3.8 deg at a 68% confidence level. Conclusions. This result slightly increases the significance for the CPT violation obtained in our previous paper (Feng et al. 2006). Delta alpha = - 6.0 +/- 4.0 deg (1 sigma). Furthermore, we examine the constraint on the rotation angle from the simulated polarization data with Planck precision. Our results show that the future Planck measurement will be sensitive to. a at the level of 0.057 deg and will be able to test the CPT symmetry with a higher precision.