丁香园AV

Synopsis

Magnetic fields are ubiquitous in the universe, observed essentially in all astrophysical environments. There are good reasons to believe that their origin traces back to the events in the very early universe, such as the electroweak phase transition or Inflation. As I will describe in this talk, accounting for the presence of magnetic fields in the primordial plasma can help resolve a major puzzle of modern cosmology -- the so-called Hubble tension. The latter refers to the disagreement between the value of the Hubble constant, or the current expansion rate of the universe, measured directly using supernovae type Ia and the value predicted by the cosmological model that best fits the cosmic microwave background. Intriguingly, we find that the strength of the magnetic field required to alleviate the Hubble tension is of the right order to also explain the observed magnetic fields in galaxies, clusters of galaxies and the intergalactic space. Our findings motivate further detailed studies of primordial magnetic fields, setting several well-defined targets for future observations.