Conferencias y seminarios

The quest for detecting Cosmic Birefringence in the CMB: improving polarization angle accuracy for ground based experiments



Viernes 17 de noviembre de 2023




Sala F12

(Edificio de Física)


Departamento de Física

Charlista: Rolando Dünner - Instituto de Astrofísica, P. Universidad Católica de Chile

Resumen: The polarization anisotropies of the Cosmic Microwave Background (CMB) constitute the new frontier in our understanding of Cosmology, carrying fundamental information about the nature of the Universe. Underlying the expected E-mode polarization pattern from the surface of last scatter, the much weaker B-mode signal can only be generated by a handful of particularly interesting phenomena, including inflationary gravity waves, weak lensing from foreground structure and galactic dust contamination. More exotic such phenomena, particularly cosmic birefringence, depend strongly on our ability to determine the absolute polarization angle response of CMB experiments. Unfortunately, the lack of natural millimeter-wave calibrators limits the polarization angle accuracy to ~0.5 degrees, which is away from the 0.1 degrees required to achieve a high significance measurement. In this talk, we will revise the state of the art of ground based CMB experiments, and then focus on the new efforts to improve the knowledge of the absolute polarization angle accuracy using novel drone-based artificial calibrators, which promise to revolutionize the way we characterize the optical response of mm-wave telescopes, and potentially other antenna applications.