Cosmic birefringence as a probe of the nature of dark matter

• Somayyeh Mahmoudi (School of Particles and Accelerators - IPM)

Understanding the fundamental nature of dark matter remains one of the most profound challenges in modern physics. In this talk, I will present how cosmic birefringence—the rotation of the polarization plane of Cosmic Microwave Background (CMB) photons—can serve as a sensitive probe of dark matter phenomenology. I will focus on theoretical frameworks in which dark matter candidates, such as sterile neutrinos, dipolar dark matter, or axion-like fields, induce parity-violating effects that manifest as measurable birefringence. These signatures offer a unique observational window into the interactions between dark matter and Standard Model particles, providing constraints that are complementary to those from conventional direct and indirect detection methods.