Primordial magnetic fields and the Hubble tension

Understand

Magnetic fields appear to be present in essentially all astrophysical environments, including galaxies, clusters of galaxies and voids.

• There are both observational and theoretical motives for considering the possibility of their origin tracing back to the events in the very early universe, such as the electroweak phase transition or Inflation.
• Such a primordial magnetic field (PMF) would remain embedded in the plasma and evolve to persist through the radiation and matter eras, and to the present day.
• As described in this Chapter, a PMF present in the primordial plasma prior to recombination could help relieve the Hubble tension.