Searching for parity violating electromagnetism with patches of the CMB sky

The Standard Model (SM) of Particle Physics predicts that the electromagnetic (EM) interaction respects the parity symmetry. An extension to the SM via an ad- dition of a Chern-Simons term to the EM lagrangian opens for new parity violating Physics that results in the Cosmic Birefringence (CB) effect. This effect is the in- vacuo rotation of the linear polarization plane of light during its propagation by an angle called the CB angle. Linearly polarized light is used to study this phenomenon and, due to the fact that the CB angle is very tiny as found by the most recent con- straints all compatible with a null value, the Cosmic Microwave Background (CMB), that is the oldest linearly polarized light we can detect, is a great case study for this effect. Several estimators based on the CMB power spectrum, altered by the CB effect, have been developed, among which are the so-called D estimators. The CB angle can be directly estimated by finding the angle that nulls the expectation value of the D estimators. It is possible to divide all the observable sky in small patches all with the same area and to estimate the CB angle with the D estimators in each of these patches. In a single patch the CB effect is assumed isotropic and the values of the angles in all the patches are then used to build the CB power spectrum. In this work, the resolu- tion of the patches has been improved with respect to past studies but, in order to do this, a high computational effort was needed. During this talk, after an introduction to the topics described above, a new paral- lel script used to estimate the CB angle on small patches of the sky will be presented. The program is fully written in Python and it is run on High Performance Comput- ing clusters. After validating the results with realistic simulations of the Planck CMB satellite experiment, that do not contain the CB effect, the Planck data files are ana- lyzed and the results are compared with the simulations. In addition to the CB angle estimates and its power spectrum, new cross-correlation between the CB and other cosmological fields are studied, like the E or B CMB modes or the lensing field of large scale structure in the Universe. Finally, new forecasts of the CB effect for forthcoming CMB experiments are obtained, e.g. for the LiteBIRD satellite.