Constraining primordial magnetic fields

Constraining primordial magnetic fields

Magnetic fields are observed on nearly all scales in the universe, from stars and galaxies upto galaxy clusters and even beyond. The origin of cosmic magnetic fields is still an open question, however a large class of models puts its origin in the very early universe. Observations of the cosmic microwave background (CMB) provide a window to the early universe. I will discuss how magnetic fields present since before decoupling affect CMB temperature anisotropies and polarization and how the damping of magnetic fields in the pre- and post-decoupling epochs leads to spectral distortions of the CMB.