UC San Diego researchers develop method to test cosmic birefringence

Researchers at UC San Diego have developed a new method to investigate cosmic birefringence, a phenomenon where the polarization of the cosmic microwave background (CMB) may have rotated during its 13.8 billion-year journey across the cosmos. If confirmed, this rotation could provide evidence for physics beyond the Standard Model and offer insights into dark matter and dark energy.

A significant challenge in detecting this rotation is that minuscule errors in the orientation of a telescope’s polarization detectors can mimic the effect of cosmic birefringence. To address this, the research team, led by Anto I. Lonappan, Brian Keating, and Kam Arnold, developed a new estimator to test the relative polarization-angle calibration of different detector sets.

The team applied this method to existing observations from the European Space Agency’s Planck satellite. The study, published in the Astrophysical Journal Letters, aims to distinguish between actual cosmic rotation and potential detector miscalibration.