Jennifer Schober - Origin and evolution of cosmic magnetic fields

Jennifer Schober, EPFL Date: 10. Nov 2020 Abstract: Magnetic fields are observed on virtually all scales of the modern Universe, from planets and stars to galaxies and galaxy clusters. Observations of blazars suggest that even cosmic voids are permeated by magnetic fields. Being correlated on Mpc-scales, these intergalactic magnetic fields were most likely generated very shortly after the Big Bang and therefore open up a unique window into the physics of the very early Universe. In my colloquium, I will review theoretical models of magnetogenesis and confront these with observational constraints. I will address the possible origin of magnetic fields in the very early Universe, during inflation and the cosmological phase transitions, as well as their pre-recombination evolution in decaying magnetohydrodynamical (MHD) turbulence. Finally, I will present results from high-resolution numerical simulations that show an efficient amplification of magnetic energy due to the so-called chiral anomaly, a standard model effect that necessarily leads to an extension of MHD at high temperatures such as in the early Universe.